Some lap time comparison data
M3/4 stat. Portimao lap 2mins 2.86 sec. 4.5 seconds faster than E92M. Unofficially, just 1sec slower than a GT3 (assuming 997).
Impressive stat, but have to keep in mind a couple of performance variables in the F80's favor --
Wider, superior rubber on the F80. 255/275 vs 245/265 for E92, PS2 vs Super Sport
(For reference Portimao is 4648 meters in length.)
Believe nearly all of the press cars are equipped with ceramics and DCT. Unknown if the old E92 lap time was done with DCT, but either way not a 1:1 with E92 brakes.
This is not to say I don't think the F80 is faster on track. Wonder by how much if it's an even playing field with tires, trans and brakes.