I am really enjoying my 3400. As with most things in high end, whether someone could live with it long term depends on their priorities. It does not quite have the mid-range magic of a good SET tube amp, but I find its mid-range to be very natural sounding, and the soundstage overall fuller and somehow more "complete" than other amps I've had, with excellent imaging as well. The bass is also tighter and deeper than I've had, though this is hard to compare with some other amps from the past, since I had different speakers in those days.
The Room Perfect is very nice, though how it important it is may depend upon the challenges of the room. Since my system is in the living room with very little in the way of room treatments, it is nice to have.
In all, I'm very happy with both the sound and versatility of the 3400, though it did take a little time to get used to the loss of the SET sound. I feel sure that if I went back now, there are more things that I would miss about the Lyngdorf. Honestly, convenience is also part of the equation. But the sonics are excellent as well, at least for my tastes.
I hope that helps.