Well, I'm not an expert by any means, but almost everything I've built has at least one FET somewhere, and I've never had any reliability problems. The only thing I've noticed is that some projects including the J201 sometimes have the pinouts wrong depending on the FETS manufacturer. As a mater of fact, I didn't even use J201's in this project since I couldn't get any localy. Instead I used a pair of 2SK55's that I found in an old cable box, and those pinouts were 180 degrees off. I'm not sure if these made any significant difference, but I love the way mine sounds. It is a little noisy though. But I expect that from a very high gain preamp.
If nothing else, this preamp is proof that you 'can' get just about any distorted sound out of a solid state project.
If nothing else, this preamp is proof that you 'can' get just about any distorted sound out of a solid state project.