I have a few thousand loose A4 papers with mostly pencil drawings, so I was eyeballing document scanners. As anyone who have tried scanning pencil can attest, finding a scanner which can handle very light marks (even with proper B/W points and warmup) can be difficult (or was, a decade ago). I figure that the situation is even worse with document scanners, which are made for office people who wants to see crisp text on pure white (and no confusing manual settings).
Pure/flat/cropped white reduces file size too, so I'm guessing that document scanners are biased in that regard, though many of them can actually do 24 bit color or 256 level gray. Document scanners rush the papers through (rather than moving the scanner head thing), so I'm not sure if the proportions will come out alright either.
Does anyone here have experience using a document scanner? They seem to be a tad more expensive than flatbed, overall. I'm not sure if you can try these things before you buy. I've considered snailmailing a drawing to a few companies and ask them to scan it, but I'm not sure how they'll respond to that.
Here's an example of a document scanner, in case you wonder what they are.