I agree....cooler denser air is always more efficient....hands down.
But roots blowers themselves are much more efficient than they used to be - even without an intercooler. Instead of the old lobe-type rotors, most blowers now have semi-helix rotors that don't heat up the air near as much as older blowers did in the day. The Magnuson MP-122 that I have on my old Camaro doesn't have an intercooler, but I'm only spinning it hard enough for 7-8 pounds of boost.....still adds plenty of power..
And as mentioned by
@vortecd, the Vortec centrifugal blowers are even more efficient and most of their kits don't come with an intercooler.......but having one is always better....
-And to the OP....good call. I wouldn't drive it either without the intercooler working either. Not worth the risk, and not tuned for running like that.