Adam Bradley, a man who visits woodwind shops!
I do indeed, sortof. I went to JP's last weekend and tried the model up - the .045 alto. I really liked it, it was solid with a nice feel to it, some character I liked the sound it produced and found it really easy to play. My only gripe was it being badly flat above top C, but I'm pretty sure that'd just be that particular sax, there's no way they'd be selling it so well if it couldn't play above top C
There's a video of the .045 on this site, and the testimonials on JP's site are all from high calibre players. I'm pretty sure that's not just hype too, as I know a guy who plays on the West End who has been amazed to see his colleagues playing these instruments. I don't know about the .042 but my gut feeling would be to look at the the .045 if you can, since it's getting so many ridiculously good reviews.