Hello Uglydog, I'm curious, what method are you using to get the specific temp numbers? I recently installed a Koso digital instrument on my 95, an alum in-line pipe, just downstream of the original thermostat housing.
So I could compare numbers to what i see on the orig equipment gauge with just Hot/cold indication.
A couple thoughts about cooling systems, as on any system, it should be clean inside, no scaly stuff, etc. Also, at highway speeds, the negative pressure on the outside of the fairing is important, as is of course the positive pressure in front of the radiator. Do you have high-way pegs, with your legs blocking part of the exit vents in the fairing? I've seen this happen on the KLR650 with guys running tank panniers.
Pure anti-freeze wont cool as well as water, but of course we need some of the additives for corrosion and anti-freeze in the winter. 50/50 works pretty well IMHO.
And, one other thought, your fan blade ok, not slipping on the motor shaft? Blade tips melted where they pass close to the headers?
Just throwing some ideas out for consideration.
Good luck to ye.