RE: Water vs water+Water Wetter vs 50/50 water/antifreeze
A quick Google search yields two quick finds
http://www.jcna.com/library/tech/tech0011.html with details and tests
http://www.jagbits.com/a37antifreezevswater.html with more info

and a bunch of other links.
I know there are some on this list that use Water Wetter, maybe they will
comment.  But bottom line is that using water only (distilled or otherwise)
usually leads to corrosion and does NOT cool as well as antifreeze mix.
Apparently some additives, to water only, improve cooling a lot, but would
still require other additives to minimize corrosion.  So, unless running
under special conditions, why not run standard 50/50 coolant mix?  Little or
nothing seems to be gained with the more complex mixes and the dangers for
freezing and and corrosion remain.