If you like it sounding like pile of poop, then its great
Mind sharing the settings you were using that didn't work?
To the original poster:
I just gave this a shot with my Thunderverb 50, an Analogman Sun Lion (essentially a fuzz face clone), and a Strat with the samariam cobalt noiseless single-coils. Bridge pickup, channel A, all eq knobs at noon. Tried the gain around noon as well, assuming that's what was meant by "light overdrive". No hiss, sounded fine with the guitar volume at 10 or backed off to clean up the tone, and with no attenuator as well as with the volume maxed and the attenuator as a master volume. Can be a little biting (I'm more a Guild/Gibson than a Strat guy), but went suitably dark by rolling off tone at the guitar. Just for fun I tried it with the gain maxed, and I liked that sound best of all. Smoother than without the fuzz, surprisingly little hiss.
I wouldn't call the Thunderverbs 'fussy'. I've had trouble with pedals with Engls, and sold the amps. I used to be a pedals in front of Fender guy, and now I use all those same pedals and more in front of the TV 50 and 200, including the Sun Lion, MXR Distortion+, T-Rex Moeller, Digitech Hardwire TL-2, Boss HM-2, Seymour Duncan Mayhem, MXR Blue Box. The one thing I don't use is either of the Big Muffs I have (Bass Big Muff and the Tone Wicker one), or the Metal Muff, because to me they just don't sound all that different from the amp with the gain maxed. I'd take the fuzz pedal in question to the music shop, try it on the new one, and see how it sounds, but so far I've yet to find a pedal that doesn't work with the Thunderverbs. In fact, I bought the 50 because I liked how the 200 worked with my setup, and wanted the EL-34 version too.