Well, the answer is not that clear or imperative, but I kind of feel so. Let me explain. "What do I need to shoot a wedding?" is one of the most often asked questions on amateur photographic forums and since I have just shot one, I feel the urge to answer it - very briefly. My almost immediate answer would be: do not do it, unless you have already done it! Having shot a couple of thousand of neat frames of your child/dog/etc., it is very tempting to offer help to a friend. But a wedding is one of the most serious assignments. I, for example, am not expert or pro at all (if you need really expert advice, head towards the website of Joseph and Mark, my personal favourite - and a fellow four-thirds/e-system user or Flashflavor, where you are instructed to use how to use flash creatively and mostly on weddings.). However, having gained a little experience along others and shovelled together tools I know, I did recently do a wedding where there was no backup. Kind of giving me the shiver down the spine, but I was not too bad. In fact, I was thoroughly enjoying it and got some shots I find neat. But I have to say, there were technical glitches all the way through, all of them worth pointing out.
So: equipment. You can shoot any project with any gear - we know that. But we also know that better suited gear will get you more keeper shots than other gear - so I'll skip the "It's the photographer" type of thoughts, if you allow me. You need a normal-wide zoom and a tele zoom for PJ shots and portrait-type/beauty shots (one of those with some close-up capability, if possible). You need good quality and relative fast lenses, so do not go below the "Pro" line. Have two camera bodies with you! This is not a luxury. Having a camera body for both lenses gives you flexibility and the much needed ability to react quickly to events. And if anything fails, you have a second body to work with. Remember that anything can fail at any time, and this is an event that can not be repeated. It is of course better to have the same type so you do not get confused. Also remember to set their controls similarly and their clocks in sync. (You would not believe how annoying is to have non-matching clocks.) My choice was two E-1 bodies with the 14-54 and the 50-200. Ideally I should have had an 50mm f2.0 and a Summilux 25mm f1.4 as well, but none of them were an option this time. The 14-54 is fine, although I find I have to knock local contrast and warm images up a bit to give it a feel I like (I have to say I would have preferred the 12-60 to the 14-54 only once: for group shots.). The 50-200 was really fine, although sometimes I would have preferred a bit less DOF and I did not really needed the reach (not the 35-100 again? grrr, too heavy...). The E-1s were performing fine, but often I missed the AF performance of the E-3. I did not quite miss shots because of the AF, but were close (that is: did not miss any "type" of shots - I did miss quite a few actual shots). Being slow is one bad thing and not being able to set a significantly off-center AF point is another. And yes: the damned AF C-S-M switch! Be sure to check you have not bumped it accidentally. I have done it more than once and performance suffers a lot, as you know.
Example of mixing existing light with strobes. Here, most unusually, strobe light is harsh. Thankfully, the features of the couple are great, so this is not very disturbing. Still, I've had preferred the flexibility of TTL and adjustment of light intensity.
As a four-thirds (=smaller sensor) photographer, you will need more light, ie. flashes (do not work without flashes, unless you have really a lot of light - unlikely in churches. I have tried and failed this.). Because on-camera flash is ugly, you'll need to have them off-camera. Because things happen kind of symmetrically in the church, you need two of them. If you can afford the luxury, have 3 of them, so that you can pop one on the camera for quick PJ-style work, while still have the two others on stands. It might turn out that the flash will be the only light you'll have in the church. I am not an expert, but putting the two strobes on stands to the side of the church facing the couple worked for me more than once (well, twice). I have used two Nikon SB-28s as I got them relatively cheap, their Auto mode works fine with the E-1 and the recycle fast and easy to connect to radio slaves. I put them on light Manfrotto nano stands. You can try to soften the light, but you lose power and recycle time. Flashes will also be used outdoors, if the couple opts for that kind of pictures (they surely will). In both cases, you will need some kind of method of triggering and given the nature of the job, you do need the wireless ones. I have to say I have used the cheap "cactus" ones and although they worked well, they gave me a bit of a headache. Despite trying out them in advance, I realised during the wedding itself that 1) the flashes were set to a bit higher power than I wanted them to work (and could not close the aperture as dropping shutter speed was not really an option), 2) sometimes the flash beam got blocked a bit, so I would have preferred an asymmetric light instead of the "patterned" one.
Although working with the "Cactus" radio slaves is a bit of hit and miss, you can get satisfying shots. However, you definitely need an assistant for this.
I was relatively successful with my relatively lowly setup. I got shots that I am happy with and I did not fail the couple. So why do I say you need an E-3 instead of an E-1? Well, mainly for three (and a half) reasons:
#1: Remote flash. I have not extensively tested the E-3 remote flash in real life, but what I have seen so far tell me that having TLL metering, but most importantly remote control over my flashes would have been great. I was careful/lucky this time, but it could have been worse. And how much better it could have been? One thing I have to add that not being able to use the E-3 in commander mode when an add-on flash is on board is beyond me. I have used a Canon system this way and found it very convenient. There should be no reason for this not being possible.
#2: Routine use of iso800. Partly rendering the use of flash unnecessary (or meaning a need for lower power), the impressive performance of the E-3 at iso800-iso1000 would have been very welcome. I would not advice anyone to use the E-1 in this case beyond iso400.
#3: Fast and flexible AF system. Although I know that good portraits are more than just pointing an AF point on the eye of the subject, the E-1 shows its age in this area the to most. You do miss quite a few PJ shots with the E-1.
#3.5: 10 megapixels. You will almost certainly not print in a size where you need 10 megapixels for a wedding shot (although if you happen to print big, more is always better). Still, because I like to crop more and more for different looks, I appreciate the freedom of having twice the number of pixels.
There is one area where I might fear the E-3: I had to pull some images because I did not get the lighting quite well and the bride's dress burned in. I could pull the E-1 raw files by almost 1 stop. I am not sure if that would have been possible with the E-3. (Oh yes, the second most often asked question: should I shoot RAW? The answer is a definitive YES!)
(PS: they were an amazing couple to work with. A big hug to Julcsi and Szilárd who proved to many that you can get married and stay relaxed at the same time!)