Ive been using an Ecstasy for some time now. The Ecstasy is a more elegant amp by far. The Uberschall is alright, but like the SLO100 I played mainly before the Ecstasy, it just didnt seem to have any character. To me anyway. I dont really know any examples of a metal band using it. It sounds closer to early EVH then to a Soldano or a Modern marshall. Its very soft like a cranked 50w plexi. Not as aggressive as a 100w. If you have Alien Love Secrets I usually say the song Die to Live really hits on what it sounds like. The intro, in my head anyway, is THE tone of an ecstasy. An overdrive pedal can help with the super saturated sound.
I have the older 100B ecstasy. At one time I almost traded it in for a new 101B but as soon as I played the 101 I had to get the 100 back. The 101 is very honky and some of the lower gain settings can be harsh. The Plexi channel on either is pretty killer for vintage marshall. The clean is amazing. At least for a high gain channel switching head. I wouldnt say its like a fender by any means. Maybe like a really great sounding marshall clean channel with infinite headroom. The 100B also has a cool built in variac. It really smooths out the sound and helps control the volume.
Thier is a lot of controls though. Mostly pre EQ settings and power section options.
I do know the GooGoo dolls use them. A little while back I remember seeing them on Conan and thier guitar player had 2 ecstasys and a few Bogner 1x12s.
My vote is for an Ecstasy.