This.I think the issue is your speakers like a *lot* of current and drive. Boulder will give you that much more than ARC tubes.
I personally would require 400+ watts on any Rockport. It's a very hard speaker to drive and will reward you when driven correctly.
I just took delivery of an 1160 a couple of weeks ago. I also have current hungry speakers (Alexia 2's) and this amp is a revelation; the Alexia's have opened up so much it's almost like getting a different pair of speakers. The sound is fast, open, detailed and effortless. Bass (Wilson's really need big current for good bass) is other-wordly. I haven't heard the Cygnus but I have heard the the Avior 2 and Atria 2 and I think the Boulder would make them sing.
I'm actually running it with an Audio Research preamp right now, although that will be the next thing to be replaced as I rebuild my (so old now it's almost vintage) system. Most likely with a 1110 but I will give the Ref 6 SE a listen as my dealer sells both.
I haven't heard the 2160 (I don't want to, I'm afraid I'll want it and the 1160 was already a bit of a stretch) but I have heard the 1161 and I can tell you it's not vaguely in the same league as the 1160 (at least with Alexia's and probably other current hungry speakers). Based on that I'd be hesitant to drop from the 2160 to the 1160 w/o hearing it first.