I played one for 10 years.
It is an Ampeg SVT on steroids. Great sound, unbelievably loud but....
Terribly HEAVY, it was almost 100 lbs with my road case. Everybody that ever helped roadie for me ,cursed the thing and hated me! Because it was SO heavy, my road case was always getting really banged up, not too good for the head either.
I mean heavy, heavy. The other problem is it takes 12 tubes. It was time to replace the tubes, and it was over $300 bucks. I bought a GK 1001RB that was a manager's special from Guitar Center and sold the 400+ to a buddy.
I miss the sound, and the ego associated with it, but I DONT miss the weight.