I run a mech. roller on the street daily, and it's the valvetrain noise that gets to ya.
Duration adv int/exh (0.050 int/exh): 285/292 (254/260)
Gross lift int/exh: 0.597/0.578
Lobe Separation: 106
The car performs just fine in traffic, but you can hear the valvetrain when idling more than anything. At least you know when it's time to reset the lash.
I ran hydraulic once, and the performance fluctuation I saw on a hot vs cold motor made me swear them off. The lifters just don't pump up as well when hot, which is just another performance degredation due to heat... much like intake air temps. If you can deal with the noise and occasional adjustment ( the locking nuts almost eliminate the need ) then go mechanical IMO.