What you should first consider is how much time you really have to sit around the computer. Scanning is VERY tedious and time consuming and may not be the most viable solution to a fast paced business. I own a Coolscan 8000ED and when scanning a 6x7 negative/slide at 4000dpi, I'm looking at 15-20 Minutes each. But these scans are from my personal outings, and I don't have a deadline to meet. I've owned numerous scanners in the past: Minolta Dual II, III, & IV, Leafscan 45 and all of them are slow and requires very careful calibration.
Personally, if I were doing weddings, I would be shooting di*g**l. Shoot a bunch, run it through the frontier system for proofing, and hand it to the customer. When they want reprints, then I would take the time to retouch it then shoot it off to MPIX or Millers labs for reprinting.
For film, just hand it to a lab and let them deal with it.
The most important thing for any scanner is proper scanning technique.. More importantly, properly exposed negatives.. Too many times have I heard people complain about a bad scanner when it is really their negative that's horribly exposed to begin with.