I have the 900 50W combo. I like it quite a bit, but the gain is a little harsh in some ways. I use a Bluesbreaker pedal with the clean channel to help give me less aggression with the gain. Works......
I have KT77's in my Komet 60. So far I am really happy as this is by far one of the best amps I have ever played through. I have a new set of Svetlana EL 34's for it, but haven't changed them yet. I have been told that the EL34's will give it a little more headroon & a lot more drive.