I am just speculating, but I would guess that the JTR subs would give you more deep bass and the D212s would give you more midbass, probably around 3dB in either direction.
Thank you. That is my thought too. I was a bit surprised to see the CEA 2010 output numbers. The surprise to me was when I was comparing output numbers from JTR, Perlisten, a poster on another forum shared output number from Rythmik. Seems the Rythmik sub bested both JTR and Perlisten. Not by a lot, but the G25 had more output.
I take the output numbers with a grain of salt as my current subs (Hsu ULS15 Mks) do an adequate job there, my goal is to get better overall frequency and tactile response. It is clear to me both JTR and Perlisten would do that. I think if I were to buy either, I'd be very happy for some time to come. I also feel if I were to buy Rythmik, I'd be wanting to upgrade again down the road.