Straight distilled will give you great results, however no protection. Water wetter if added appropriately won't offer enough protection alone IMO, but will actualy give you better results than straight distilled.
Adding water wetter won't give you much corosion protection either and after some time the water wetter will gum up. I have sceen several people use it in comupter systems (it is what I would use also) but eventualy it looks like stuff floating around in there and it needs to be changed, it has even gummed up some peoples water blocks pretty bad...
I like Engine Ice the best for the banshee. IMO it is the best all around, and it's non Toxic which is definately a plus in my book, specialy when it comes time to change it. It also works very well. I get better results with engine ice than 50/50 mix of collant and water + water wetter .
Water wetter on the other hand, is EXTREAMLY toxic.