Hello and welcome to the forum.
I had a 2008 SD. Bought it with 5k miles, rode it for 6k miles until I crashed it. It was a great bike. The insurance gave me a good payout so I was able to buy a 2008 SDR with 4400 miles on it. Today, I clicked past 6000 miles.
I'm not sure what the price premium is compared to the SD.
The SDR is pretty raw. Harder suspension, More vibration to the handlebars due to lack of rubber mounts. I sort of wish it had a dual seat. The stock seat is rock hard, the PowerParts seat is as hard as a 2x6 wrapped with one layer of rubber inner tube.
Power, Not sure I can detect the difference. My SD had Leo Vince pipes, BMC air filter and had been remapped using TuneECU. It also had the KTM Gel seat. My SDR has a PowerCommander 3 installed and MotoHooligan Air Box, FMF Apex pipes and the seller claimed 142 RWHP. That would be a very healthy SDR I think. I've never had it to a Dynamometer so I don't know the true numbers its putting out.
I recently changed the rear sprocket from a 38T to a 40T and I can feel better pick up, and 2nd gear snap throttle wheelies but I'm pretty sure it does not have 142 RWHP.
Given that I was able to ride the SD for 6 hours or more without soreness, I'd prefer that, instead of having to stop every couple of hours to walk around due to the hardness of the Comfort Seat. Comfort. Yeah right.