In reply to conorcussell:
Realize that a major reason why the Fusion doesn't do as well on ice [as compared to the Viper] is that it comes with the Fusion drytooling pick and not the svelte Laser ice pick which comes with the Vipers. The difference is significant. Put a pair of Lasers on the Fusion tools and they'll perform considerably better on pure ice.
I have both a pair of Vipers and a pair of older Fusions (have climbed on new ones as well). I feel the true ergo style tools make climbing at a given grade substantially easier. I use my Fusions for all style of climbing, including mixed, pure ice, drytooling and alpine. The thought is that the z-shaft tools aren't good for alpine as they are harder to plunge. While they are harder to plunge, for the most part the routes I do aren't dependent on plunge-ability. Plus, if the snow is soft enough I can still plunge, if not, I just dagger. There has been a reluctance for people to get ergo tools because of their concerns for alpine, but remember this was the same mentality when we moved from straight shafts to bent shafts and eventually curved shafts on ice tools.
Fusions with Laser picks are phenomenal. The picks will hold up to most all mixed climbing (I'm 90kg when mixed climbing, without a pack) and I've torqued the hell out of that Laser pick on numerous occasions and never had it break or bend. Anyway, just thought I'd add that.