AGD certainly gets high praise consistently. I believe the Tempos are around $5k and at that price point another GaN amp that gets high praise is Atma-Sphere class D. You can search comments in this forum about how owners of Ralph's tube amps have switched to his class D. It's also a stereo chassis, larger than Tempos I think. I haven't owned (nor heard) Atma-Sphere equipment but Ralph (who is active in this forum) is certainly knowledgeable and gets good comments on customer assistance (two traits you noted are valuable to you). Worth looking into, I think.
Could you please elaborate on the differences in sound between the Tempos and LSA Voyager? It's clear the Tempos are better overall, in line with the price differential, but I'm wondering if the differences you noted were centered around bass, midrange, treble or other.