As someone who has drum scanned thousands of negs over the years, I'd have to say that if you're looking for the ultimate in quality, you do want drum scans, but you want to find someone who really knows how to get the most out of his/her scanner and has samples to back it up with. Not every drum scanner is equal to another and most certainly, not every scanner operator is either. If you're going to be sending your film away to scan, it doesn't make much difference if it's across the state or across the country.
When I drum scan black and white negs, I typically scan at 4000 ppi unless there's a special request for more or less resolution. The drum scanner I use scans at 8000, 4000, 2667, 2000 and on down, but those are the most relevant and most used resolutions. I always make 16 bit per channel RGB tiffs that are neutral and in Adobe RGB, unless requested otherwise.
I've been able to make fantastic drum scans and subsequent prints from negs that I could never make a satisfactory print from - from all sorts of negs. Slight under or overexposure is no problem whatsoever. Gross overexposure - negs that would be impossible to print in the darkroom generally scan exceptionally well with maybe a bit more grain than you would expect. Underexposed negs really depend on the neg, but a good working drum scanner is capable of recording all the detail on the neg and separating in a way that would be completely lost in the wet darkroom.
16 bit drum scanned tiffs from film are much tougher than any digital camera file you've ever seen. Both the grain of the film and the nature of the drum scan see to that. Even an 8 bit drum scan generally has no problem being twisted around in post, but since the scan time is identical for both, there's no reason not to - and beware of anyone who charges you double for a 16 bit scan just because it's a bigger file. As I said, at least on the Howteks, the scan time is the same.
Negs are taped to the drum in a sandwich made of a layer of mylar overlay material with scanning fluid filling the space between the drum and the film and the film and the mylar. The mylar is then taped down around all four edges, sealing the fluid in so it doesn't get all over the scanner. The fluid prevents Newton's Rings, but also makes sharper scans and fills in micro voids in the emulsion. It's a good thing. In the old days of prepress, they actually used Johnson's Baby Oil - where the term "oil mounting" came from, and then they used to soak your film in film cleaner and leave it between the pages of an old telephone book to absorb the Johnson's (I've seen it with my own eyes!) Today, most scanner operators use Kami fluid, which is a naptha based concoction. A lot of people will tell you that Kami simply evaporates with no trace, but you do need to do a basic wipe with PEC-12 after. You'll have no problem in the darkroom after that, if you ever need to.