For me it would be my Maggie MG1 Improved....they were very sweet with my HK tube amp/preamp. OTOH, not in any way in the same league as my current SF GH's. Lloyd, why not acquire another pair of GH's? They still come on the market once in a while. Perfect for that second system in the smaller room....or maybe even in your existing room with a Sub. Would give you a different "flavour" to your X1's.
If we had room for a second system, maybe...but i've always preferred to concentrate everything into the best possible system. So that's what i've done to date. If/when the main system is 'final'...AND if there is an appropriate place for a second system, then maybe. But for now, perfectly happy.