Currently own a pre-96 XR-R, and a DRZ-250.
I like the XR-R. Big differences were R had an oil cooler and slightly different cam. Oil cooler to help cool it on slow trails. L had taller tranny gears in 3-6th gear for better highway manners. The R doesn't have the stator capacity as the L does so lighting can be tricky but doable. I'm running LEDs everywhere. There were some slight differences in the suspension but you may not notice if you're not riding hard.
My R will be street legal as I bought a L frame w title and changed everything over from the R. R is kick start only, but it starts easily even after sitting for a couple months. 2-3 kicks at most.
Depending on which DRZ you have, the 250 or 400, the R will seem a little lighter and more nimble.
plating depends on your state. You may be able to buy one from another state and bring it in but you'll have to verify that with PA. You can look at the flea market here or ebay to find small DS bikes.
a recent thread over on TT discussed this very thing. Good luck