I put a lot of offroad miles on my dr250. Its a good bike, btu not quite as nice as the dr 250. Its the same size, and weight, but less power. Suspension is fine, but soft for fast work TONS of hop ups available for these. Many old rm parts will switch over and bolt right on.
The oil level is tough to check as it takes a special procedure. Most people overfill them.
This guy can tell you more about the dr bikes than you ever cared to know. He knows the 250 350, and 650 inside out..and then some.
http://www.kientech.com/