[Boatanchors] sb-220 vs Johnson Thunderbolt?

[Eugene Hertz]

Hi there, I know this is a loaded question but I was wondering people's opinion of the Johnson Thunderbolt vs a Heathkit sb-220 for an amp. Areas of comparison I'm interested in are:
a. Ease of use
b. Reliability
c. Availability of parts/Final Tubes
d. Ease of repair (ie room inside for knuckles) 
e. Linearity and quality of sound (ie good reports)

I looked on eham.net which had great reports of the sb-220 but had no reports at all on the thunderbolt