Are you retiring from climbing at the end of 2011, Fletch?
Cos what you buy might depend on what you do beyond this year. I agree Nepals might not be warm enough for Elbrus, from what I've heard of there, though fine for Rainier and Orizaba, and maybe OK with -40Below overboots, so long as you can put them on warm in the hut and your crampons fit over them. Baruntses would be a lot better for Elbrus, and not too much overkill on Orizaba or Rainier.
Spantiks are great boots, but overkill for anything in the Lower 48 or Mexico, and you've already done Denali. They'd just get trashed on Aconcagua, in case you're thinking of that, and they're not really warm enough for an 8000er, especially Everest, and they're not nimble enough for ice or technical climbing at home. So you probably don't want Spantiks.
Dane's coldthiste.blogspot has heaps of info on Baruntse vs. Spantik. They seem like a good intermediate step for most people between single boots and Everest boots.
Incidentally, almost all modern boots (not looked at the newest Scarpas) are actually way too stiff and technical for what many climbers are doing, which is mostly hiking. Nepals are good boots for technical ice and mixed climbing where you want stiffness for frontpointing. They are not the best boots for comfy hiking, and Rainier, Orizaba and Elbrus are all hiking - just hiking in snow and low-angle ice. There are other (single) boots out there that may be more suitable for what you, and most people, are doing than Nepals.