I had a 300 and then purchased a 510... the 1500 replaced the 510. If you're using it for business
and personal, get the 1500. My 300 jammed frequently when about 8 or more sheets were loaded at a time. Forget loading more than a couple small receipts at a time. The 300 is great for portability, but the 510 is much better at handling larger loads and different sized sheets and is quite a bit faster. The 1500 should be even better.
For photos... It's definitely not a photo scanner, but I've scanned a lot of my old photo album photos directly into iPhoto and got rid of the originals. Very quick and easy. The quality isn't that of a flatbed, but I'm not anal about picture quality as some are.
--If you're interested in what a scanned photo looks like from my 510, private message me and I'll find something to scan for you when I get home.
I've never had any photos scratched/torn from my 510 (haven't tried photos on the 300). The only thing that has been torn are docs that I forgot to unstaple.
Haven't tried Paperless. I usually just scan to folder (doesn't work in Snow Leopard, but there's a
fix coming this month). I just downloaded the trial version of
Devon Think but haven't had the time to try it out yet. I imagine it works well with the scanners because Devon sells the ScanSnaps with their software as a bundle option.