Having owned a 6sp zhp for over a year I can tell you that it is fast. I too drove the demo 330i 6sp that all the dealers have. I can't say that the e90 is much faster, but you could tell it had more hp. As stated earlier, I think a scientific test by C&D would tell (they correct times for temp and alt).
I can tell you that the zhp's lower gear ratios give it an advantage even with lower hp, this may be why we can't tell using the old butt dyno.
As far as handeling goes, well the zhp may be tighter with its m3 suspension parts and big wheels (actually the same size as e90 sport package, but the michelin pilots are better). I do think the new 330 handled great, but it wasn't quite as crisp. That does translate into a better ride.
With all this said, we must remember that the zhp is a low production model specifically designed for performace (hence it's true name "performance package"
) they only made like 4500 of them.
By the way, I belive that the Silver demo 330i is equiped with the Premium Pkg, Sport Pkg, 6sp and listed for about $41.2K.
My 2 cents.