Boris, I recently did exactly what you are planning and experimented at a friends wedding, knowing that they had already hired another photographer for their formal shots. I decided to "have a play" and used Fuji Press Pro 800. The resulting grain was a pain in the butt. It wasn't significant enough to look "artsy" but was too much to look "good". Also, the skin tones were TERRIBLE. My bride looked blotchy and even as though she had a fake tan in places, whereas shots I had just taken on a different camera with the same light and equivalent exposure with Fuji NPH 400 (my fav. wedding film), looked gorgeous. I have never used the TMAX film, but I wouldn't recommend shooting anything for a wedding with film faster than 400 unless you are going for a REALLY "artsy" look and "using" the grain for its creative/artistic merits. And don't even think about group or family photos, as you can just about guarantee that people will want enlargements of these, which will of course look shocking with the grain. My preference would be to take a tripod and shoot with a 400 speed film. If you look here, I did exactly this for this wedding, which was another friends and at which I also let myself do a little "experiment". These shots were shot handheld (and leaning against poles/church pews etc in place of a tripod) using only available light, in a dark church with a 135mm prime lens, and T400cn film. Not what I would refer to as my "best" work, but an interesting experiment nonetheless...
http://www.tanyamayer.com/themarriage/churchbellsaringin/churchbellsaringin.html Good-luck! tan.
