It really isn't a pain to drain/fill the system seasonally. I did it recently when I ventured down south to run Sebring in January. Had to refill when I got down there, raced, drained, and came home to the glaciers
Hardest part is bleeding the air out of the system, but I've got have a procedure for that as well.
I've been told that a very weak mixture i.e. 10% will keep from freezing in moderate temps, but doesn't present the cleaning mess. If it's cold enough to need anti-freeze, I suspect overheating won't be an issue.
The main issue of factory specified coolant is the corrosion protection. Distilled water helps. Most of the FF/FC drivers with the cast iron pinto motors run plain water with no problem. You may have to replace your water pump every 4-5 years due to corrosion or lack of lube but that shouldn't break the bank.
FYI - my water pump and T-stat looked fine on my 5-year old motor that ran plain water & water wetter. I drain it every winter.
[This message has been edited by Greg Gauper (edited March 19, 2004).]