Thanks Stephen. The "push to 1600" pics look promising but key to a meaningful comparison is the new TMax pushed to 1600 compared to, say, Ilford D3200 at 1600, Fuji 1600 and TMax P3200 at 1600. If you know the light conditions demand 1600 then, unless you can risk developing the whole film at the 1600 time with no loss of quality, you sacrifice the portion of the film shot at 400. You could of course simply eject the new TMax400 shot at 400 and insert a new TMax400 which you push but this doesn't gain you anything compared to inserting a high speed film unless the pushed TMax is a better film at 1600 than the three high speed films mentioned.
I'd certainly like to see a comparison