I don't know if the Bogner XTC has more gain than the 5150, but I have a 5150 and know that its lead channel has more gain than you will ever use. So any more would be super overkill.
I would recommend not using the amount of gain the amps can produce as a factor in making your choice.
XTC lead channel is supposedly voiced similarly to the Uberschall. You should be able to get insane, excessive, ridiculous amounts of gain with that amp. I've never been lucky enough to try one but I think if I could afford it I would have no problem buying one sight unseen.
I've heard the Ecstasy is a bit of a loose amp, great for leads - that's really vague, I admit, and could be off, so I highly recommend trying one! (easier said than done, of course)
Eh, somewhat, but nowhere near Recto levels IMO (though pretty much all of my experience is with my old 5150 combo, so naturally that's gonna be tighter than running a head through a Recto cab!)