To me it seems Tv2 is a tighter fit for the ball chamber due to the fixed height locking screen.
Tv1: I can get 84 * 2.5mm or 44 * 3.0mm shaking/settling as they're put in.
Tv2: 84 * 2.5mm or 44 3.0mm, while possible, is much harder to fit requiring even placement at start and shaking/settling as they're put in once past the critical start area.
Either way, both heads seem about the same in number of balls.
I do like the added overall mass of the Tv2 head and the larger bowl which seems to distribute the heat a bit more evenly.
Currently running side-by-side Tv1 and Tv2 heads on Tv1 stems with 44 * 3.0mm Ruby balls in each with Wand as heater using v2 Wand Adapter.
Tv2 head improves on the already great design enough that I can say for certain I will be ordering a second full device and a few extra heads.