[x10guy]

I don't think whatever we say will convince him.
The best solution is just let him flash a ROM without TF3D and let him be happy with the ever so slightly faster TP.

It's probably that he is still very much in the Mogul/Vogue state of mind. The "original" stock ROMs in those devices were slow and crippled (originally no GPS). Flashing custom ROMs made it an entirely new device.
The out-of-the-box experience with the TP is much improved. It's still nice to be able to flash custom ROMs / kitchens but you are not going to see the same magnitude of improvements as with the Mogul/Vogue.