#1: MOST expensive kits are all maple or all birch. the days of exotic woods are largely gone. yamaha has a few different lines (maple, birch, beech, oak). premier has a few interesting kits (gen-x shells = maple/birch combo). pearl's custom shop will use mahogany if you want them to. these are all the exceptions, though, and homogenity is the name of the game at the moment. ludwig has moved to all maple. sonor has stopped using beech for their drums (and the beech they used wasn't the same as the yamaha beech -- completely different, in fact). the factory that made the maple-gum combo shells for gretsch closed semi-recently.. i'm not sure if they found another supplier for the particular shell. if i'm not mistaken, fibes (a custom drum shop in austin) has the machinery now.
really, though, if you want interesting shells, you've gotta go boutique or settle for the few big name options (which aren't bad, but they're more samey than, say, a nice old slingerland 3-ply mahogany kit).
most boutique companies (and this includes overhyped places like Orange County Drums and Percussion) use cheap plain keller shells and cheap taiwanese hardware.
www.drummaker.com -- save yourself a few thousand dollars. I built a nice little kit for less than a grand that'd cost probably three times that at OCDP.
#2: bearing edges don't necessarily mean a cheaper drum (and i'd disagree that they're easier to tune), they're a different philosophy of drum design. old slingerlands, for example, had rounded off bearing edges. i'd say as long as the edge is true, it'll be relatively easy to tune. also, heavier heads are easier to tune. less overtones.
#3: DW makes their own shells. they started off using keller shells, though, which are fairly generic.
to answer the original question: if the kit is maintained well, has good heads, and, MOST IMPORTANTLY, a good drummer, then it'll sound good. better kits (more expensive, generally, but not universally -- but sometimes it's a good indicator) wear and tear better, come stock with better edges and better hardware, and, to be honest, probably inspire a better performance out of the musician behind them.
but if a guy shows up with a beat up set of pearl exports, don't fret. he might rock your shit.