Well, obviously, if it's an indoor range they'd probably have problems with the smoke. Otherwise, it works pretty much the same as a cartridge revolver, except it takes a long time to reload.
I've never used Wonder Wads-- I'm thinking of getting a C&B revolver again, but when last I used one I didn't know Wonder Wads were available. Maybe they weren't. I'd definitely recommend them over grease, it makes a MESS.
Speaking of mess, BP makes one. You'll have to get used to scrubbing your disassembled revolver in hot water and dish soap, assuming you're not using one of the cleaner substitutes (and not all substitutes are cleaner). It is not that big a deal provided you use good hot water, so that it evaporates off nicely, and of course oil things down once you're done.
Other than that... unlike smokeless, with BP you want to fill the space between primer (or cap) and the bullet/ball/whatever. You should be able to fill it with BP completely, although this makes for more recoil and so on than you really need. If your revolver's rammer will let you seat the ball directly against a reduced load of powder, that's OK. Otherwise you can fill the otherwise-empty space with wads, or some kind of filler or other. A friend of mine always used corn meal for that purpose, and while I wouldn't recommend that for a load you intended to leave in the chamber for a long time (because I think the corn meal has some moisture in it, and moisture against your black powder won't do any good) it worked fine for immediate firing, as you do on a range.
The Colt open-top cap and ball revolver design doesn't have the strength of a solid frame, but it does allow a greater proportion of the fouling to blast away than a solid frame would. Mine were subject to trouble from spent caps, however. Sometimes the fired cap would fall off and get wedged between hammer and frame. With the big Dragoon this didn't matter much; it would just mash the cap flat, and I'd find one or sometimes two mashed caps in there, buried in the powder fouling, when I cleaned the thing. The little 1851 Pocket .31, though, would jam right up from one cap.
There's an old movie gunslinger move you see once in a while, where they point the revolver straight up to pull the hammer back (if I used the proper word for this operation, the idiot bulletin board program will censor it) and then bring the revolver down to take aim. The result of pulling the hammer back with muzzle pointed skyward is that any fired, split cap that's going to fall off will fall away from the revolver rather than down between hammer and frame. I suspect this pointing-skyward move really was used in the old days, for just that reason.
Mike