Thanks Dave, I'm going to take a look at the Engl and the Brunetti. I've already had a look at the Rivera on their website, and I like the sound a lot. Sadly they are quite pricey - I'm still annoyed that I didn't have the cash together when Dakine sold his KR55.
I was bored in work today, and had a look at the Peavey site, and discovered, on closer inspection, thaT the JSX doesn't have reverb on it. What an odd thing to leave off a £1200 head. Might be because Satriani uses some sort of rack reverb unit, but for God's sake, put it on the amp so the rest of us have the option. What might have been a contender has now faded into the background, especially given some of the useful suggestions made here.