My understanding is that statistically, as a group, mutts (real mutts as opposed to designer mixes) are healthier than purebreds, as a group. That actually makes sense, because some of the breeds are genetic disasters, and because so many purebreds (and crossbreds) are milled . . . so both the really screwed-up breeds and the mill puppies drag down the average. But that in no way means that any given mutt will outlive any given purebred . . . if you are really looking for health above all, your best bet is to get a purebred from someone who has bred for just that.
Again, from my understanding, its not that mixes are healthy and purebreds screwed up . . . its that purebreds, collectively, are slightly more likely to be screwed up and to be screwed up in predictable ways. Mutts are slightly less likely to have serious problems, but its a complete crapshoot what those problems will be if they do have them. So I know to keep an eye on Docket's vision, his hips, his back, and getting weak behind. Sarama . . . errr . . . I have no idea what I should look for. Asian spitz problems I guess . . . but since we only vaguely guess the other half was possibly from the herding group . . . hmm . . . yeah. If she has an inborn problem . . . it could be anything. I tend to keep an eye on her back because she's ever so slightly swaybacked.
Dekka . . . about those moose . . .wouldn't they be especially vulnerable to an introduced disease?