It works out that a volume of NPG+ is only 17% less efficient than the same
volume of 50/50.  Once hot, the vescosity is not an issue, being only
slightly more viscous than water (no system change usually necessary).

From the reports I've seen, it has to be true that there isn't a huge
difference in cooling performance.  Ken Welter has already stated that he's
changed back and forth a couple time, and didn't see any real diff in temps.
Loads of folks with RX-7's use it, and also don't report any dire
consequences.  At the same time, I'm not sure there are global cooling
improvements to be made either.   I believe the benefit of being able to run pressure less, coupled with
higher boiling point makes it worth trying for me.  Now if I can just find
some.  Have you found any good online sources?  Most of my normal places
don't carry it.   Cheers,
Rusty (engine repair status- one week down, and going nowhere fast)