I don't agree that it's 'rip your arms off' more power than a a 650sx unless you are comparing an all stock 650SX to the SJ. The 650sx with a carb, pipe and prop wasn't half bad. My Stock '04 SJ doesn't exactly impress me in power. I certainly wouldn't call it an arm yanker.
It is going to be a huge upgrade in handling and performance. The SJ hull is a much better ride. The weight is about the same but the handling is greatly improved. The all stock SJ is nothing to write home about, but it has a lot more performance modifications available and has a huge power potential over the 650sx.
I just don't want you to get on it and feel disappointed in the power. A stock SJ isn't much more powerful than a 650sx with a pipe, carb and prop. But a SJ with a pipe carb and prop is much more powerful than the 650sx.
Plenty of people will disagree with me. My 650sx ran great until it ingested water. It was just a carb and prop. I wasn't impressed by the power of the SJ. I was very pleased by the change in handling. Now I have a few parts and it greatly out performs my SX is every way.