The thing is what I really want to do is a DVM/PhD, but I didn't get into any. By doing the PhD first, I have a chance to reapply to a DVM/PhD and see if I get in. If not, then I could try applying for med school (I will not pay full price for vet school). I already have a master's, so I don't anticipate my PhD taking longer than 4 (at most 5) years, so the timeline is only extended by max 1 year, if at all.
I am passionate about evolutionary psychiatry, animal behavior, and psychobiology research, which is not necessarily the closest relative to human medicine. So pursuing a biomedical PhD in neuroscience, related only to human health (and using invasive animal models), is quite a stretch for me, hence the difficulty. It's really difficult to turn down the MD/PhD scholarship, however, as if I don't get into the DVM/PhD the second time around, I'll have to pay in full for med school (granted I get in again!)
In terms of hiring, I would like to do animal behavior focused research and practice psychiatry (stretch, but not so much) unless I can do veterinary. So is doing a PhD at a med school that's more far removed from my research interests (they are quite stable, it's not just a topic of interest) going to harm my chances at focusing on the research direction I want in the future? That's the difficulty. If not, then I'd just go with MD/PhD, and toss my slim chances at the successful DVM/PhD application.
Thank you for all the replies by the way! I am just using this as a place to express my ideas and get some unsolicited opinions. By no means will I base my decision on what others say, however, but I do appreciate the insight.