I can share some results for those who will come across this.
I received my Altair G2.1 - and after 8 hours of break-in, I can tell you some initial impacts and comparisons vs Altair G1.
Using the same Power cable, XLRs between the two units. With both on dynamic, upsample max ~360K
While the Altair G1 is still an amazing unit, the Altair G2.1 shines if you truly have a transparent system. I have found more detail, more bottom end, and more stage.
Is it worth double the price? $3249 vs $6099 depends on your budget and system. You are not at a loss Buying a Altair G1 over the G2.1
I would invest in a few things first - Like Shunyata power distribution and Low Noise power cables, Cardas XLR and Speaker cables, A good quality Amp and preamp and speakers.
(Note: Avoid synergistic research not worth the money or the hype)
If you have all that then Yes - Get the Altair G2.1!