I can't really answer your question. I have a Sonic Frontiers SFP-1 Signature that I am about to send out to the Parts Connexion for some upgrading. I have a SF 2 Power Amp and think that the SF components are fine. Everything I have read (there is a fair amount of info on the 'asylum) about Chris Johnson's mods has been very positive. Personally I would think that upgrading the SF and then taking advantage of it's tube rolling abilities would make it worth keeping.
Chris
Chris