There is nothing wrong with the DR650, but it's not at all comparable to the CRF250/CRF300.
As far as wet weight is concerned, the DR650 is about 45 lbs heavier than the CRF300L, (357 lbs vs. 311 lbs) and especially in the dirt, every pound counts. Also, the Honda suspension and chassis 1) construction and 2) design is light years ahead of the DR650. Additionally, CRF300L can have ABS and is EFI (carbs can be a PITA if you don't know "how to carb"). I've got a load of experience riding big and small bikes off road and there is no way that I'd go for a heavy bike if I wanted to spend any amount of time riding trails. When you ride a heavier bike off road—
especially as a new rider—the "effort" and "risk" curve grow exponentially compared to a smaller, lighter bike.
The DR650 is more long distance road oriented, but can handle moderate dirt. The CRF250/300 is much more dirt oriented, but can handle moderate amounts of road.
Getting a temp bike to ride for the season is a totally legitimate strategy, in fact, it's a great way to go since you'll be able to more closely hone in on just exactly what type of riding you'd like to focus on. If you get a DR and find that you hate how heavy it is on dirt, you know a lighter bike might be right for you. If the DR's discomfort on the highway drives you nuts and you don't find yourself doing as much dirt as you thought, maybe a more road-oriented bike would suit your use case better.
My final bit of advice it to just make sure you don't buy a piece of work that requires you to pull your hair out wrenching on it instead of riding—that's the worst!
Private party inspections by specialist motorcycle shops are well worth the money if you don't know motorcycle mechanics reasonably well. They've saved me from buying absolute money pits in the past.