Check the tank for rust.
That'd be about the only problem that'd be a show stopper - well, O.K. it can be fixed, but it'd be a PITA to deal with. (Having to seal the tank, maybe a new pump, do the external filter mod). The newer ones went to a slightly beefier alternator, dual spark ignition and later still ABS. Only the ABS was a significant improvement, and only if you want ABS. The latest (2012+) model is a real improvement, but it'll be a while before they are cheap second hand.
The DL's are solid bikes, that's about the only problem I can see other than needing to check the rubber bits for cracking due to age, but most of them don't have problems like that anyway.