you are only getting yourself confused here (is300h better than a GTR, sorry...what), if I put up a link of my car going through the gears you could clearly 'hear' it was more involving that the is300h you have.
I need to find out a way to get my dash cam shoehorned into the engine, for the real benefit of as manual is you are in control of the dynamics.
The auto boxes used in the is250 and ISF are fantastic, but I don't want a auto is250, its no better than what I have right now.
I would be pretty confident my is250 would easily do a lap of the ring faster than a is300h, cars like a ISF and high end performance cars will blow away a is300h.