I was using a Sunn Coliseum-300 amp when I had a chance to try a Genz-Benz Shuttle 6.0 into one of their T-12 Shuttle cabs. I thought I barely had it set to a moderate level, but when I hit a note it overpowered everybody warming up. They all stopped and asked "what was THAT?"
After that gig I told my wife what I wanted for Christmas - that Shuttle 6.0 and a pair of T12 speakers. That was more than 10 years ago. I upgraded the Shuttle to a 6.2 to take advantage of the newer voicing, but that's all I have needed to do. I sold one T12 speaker and picked up a 2x10 (T210) Shuttle speaker on a whim. Later I picked up a used Genz NeoX212 cabinet, but that was sheer dreaming on my part...that cab is capable of cruel loudness that I'll probably never need. I know amp ratings are highly undependable, but the rating on that Shuttle 6.2 is 375W peak into 8 ohms, 600W into 4 ohms. I can tell you that it sounds like EVERY BIT of that power is present at all times. I have never wanted more power on any gig I have played. At 3.75 pounds, that amp is a wonder.
I have a Fender Rumble 100 for practice, but the gig rig is the Shuttle and whatever combination of cabs I need. My band isn't a silly loud one, and I'd use a single T12 for anything up to 100 people, but I'd play to a whole gym using the 4 ohm NeoX212. I like the tube preamp which can produce some nice driven tones, or you can keep it very clean. I always play with flats, and that combination works extremely well with the Genz Shuttle.
The Genz Shuttle hasn't hiccupped in 10 years, and I have no expectation it will in the next 10. It's extremely well built.
^^ the guy who designed the Genz Benz Shuttle line also designed the Mesa Subway line, and is a regular on these forums. I very much enjoyed my brief experience through a loaned Shuttle 6.0.