That's not at all what he was implying. However, with less power consumption and less heat, the 5750 would be able to overclock higher and faster. The GTS 250 is a standard 512mb card with 256-bit GDDR3 bus. That means that the 1GB card won't even see hardly any benefit at all over the 512mb version because of that bus limitation. Not to mention you are basically buying the age old 8800GTS with a new name and new higher price and only DX10 support. The 5750 is a brand new card with DX11 support and a standard 1GB card with GDDR5.
You should also know that PhysX is not even supported by every game and that even when it is, it really only affects a few minor things like particle flow and water.
ATI wins this round dude. The 5750 is better than a GTS 250. Physx are not a huge deal at this point anyways. less than 2% of games support physx, so that is irrelevant.