For what it's worth, this is my experience/opinion.
I have an '07 SD. Over time I've done the usual mods - Full Akra system, Motobox etc. and I've been out riding with Klinks, (legendary '06 bike with very high milage and high dyno figures) and Shade, (SDR with way more power, (in his own mind and enthusiastic reprts ) than his previous SD. But everything all comes down to how fast you are willing to open the throttle. They ride fast. All the time. Me....I'm older and a bit lazier. I think that I worry about the consequences of crashing more. (I've had a few bad ones over thirty years, ha ha). I know that at times they leave me and I have to catch up. But that's not down to engine performance. It's me. Sometimes I have been able to catch them up on straights - just through hunching down more and nailing the throttle. Is that because I have a faster engine? Or just because I happened to nail it for 300 metres longer when they backed off a bit because of a rabbit running out of the hedge? I don't know. And don't think it matters that much. In the real world we are all limited by other factors rather than BHP and torque charts. Really.
And a few years ago my SD in standard suspension set up professionally with Racetec K1 tyres was brought back to the Bracken workshop by an enthusiastic Paul, (yes, the cynical, miserable Paul who is hard to get a good word out of), and I was told that I had the best handling, best set up SD he'd ever ridden. He was really impressed and told me to never change it. Must say, that period was when I was doing my first serious track days and I was really getting into it. Confidence very high.... and I never worried about set up and handling, just a few extra clicks of preload and rebound for the track. Then I thought I'd get more serious and get an SDR shock and start "improving" things by messing with the forks in the clamps and stuff. But ever since I'm not sure if things are better really. Still set up well by the guys at HMRacing for me but on track I have never felt the bike was a neutral and, well just effortless, to ride. Like all you lot...we want to believe that the mods we make always make a better bike. But maybe it's not so. Just because it's an 'R for racing" shock doesn't necessarily mean that you will like it better.
Anyway, rambling over.