I love my Finally for Bass, Guitar, and Synths.
For use with Guitar (or Synths), I strongly recommend using a 12AY7 or 5751 in the Finally, rather than a 12AU7.
I've been rolling different 12A_7 tubes through my Finally. Started with a 12AT7 and I've slowly working down in gain factor from there. Lately been digging the 12AY7 - stays mostly clean with just a little bit of hair when really pushed. I just got a 12AU7 to try out next - I've read that the character of the breakup isn't as nice as some of the others, so they tend to be more suitable for clean applications.