I also have the JFET and agree with everything Jimbo said above. It's a great pre and an incrediable deal. Altran, who builds the transformers, also makes them for one of the Old School Audio models.
If you search the message board at
www.tapeop.com there is a lot of info and glowing opinions of the Hamptone preamps. There are also a few songs tracked through the Hamptone posted by a guy named dynomike.
There is also a review at
www.mojopie.com
over all the sound is "big", "warm" etc.... like a "cleaner" Neve maybe. I've read where someone who owned both said it sounds like a "better" Focusrite ISA. Other people have said it is like a slightly more colored John Hardy, for what that's worth... Everyone does agree that it's really versitale and a great preamp though.
Good Luck!