My guitarist owns a powerball and an invader....and out of the two...i think the powerball won me over.
Nice and tight, and the gain, oh let me say, it starts off where a triple rectifier left off!
Needless to say,im thinking about selling my mesa for one.
The invader sounds just as good as the powerball if ya throw some EL34L's in there. Not quite as ballsy as
the powerball with 6l6's...but pretty damn close. He actually threw some 6l6's in the invader and biased it up
and it sounded even better. But due to one post on some forum about how that could ruin it somehow, he put
the EL34L's back in.
I know these werent the particular models you were looking for, but it may help.
Also both heads are solidly built and come with built in noise reduction!
Not once have either of them gave him any troubles what-so-ever.
Also a few days ago, musiciansfriend had a scratch and dent sale on a powerball for like $1300,they might still have it.