Re Superfly – you don't NEED G2 forks – that's just how it's intended to be used.
I've got the Niner rigid carbon fork on my Superfly hardtail, and prefer the handling with the 45mm offset compared to the 51mm G2 Fox fork that was on it. I supect however that's partially due to the fact that the rigid fork steers less sloppily….
The aftermarket 29'er forks from Fox/RS are 44mm offset now I think, so a "compatible" bolt-thru fork is available.
The other option would be to swap the lowers on the G2 fork for a bolt-thru version.
I'd loooove a shot on a Tallboy though..