Just stopped by the tint dealer and they have a heat gun demonstration of the 3 tint choices they offer. The top of the line, Huper Optik Drei is incredible. Where the other tints still allowed quite a bit of heat through the glass, the HO Drei was actually cold to the touch. Comes with a pretty incredible price too...regular price $599; knocked $499 off if I buy in the next 10 days.
Just not sure it's worth spending that kind of coin on tint, when the standard "limo tint" is $199. Moreover, both Huber Optik products they offer are much lighter than the limo tint. I would guess 35-40% is the darkest they go.