Personally, I like the chest piece of 1, design's 2 looks like the body can be split in two, if you experiment a bit with that it could result in one interesting enemy type (Though the fact that it's based on a deer interests me enough).
I don't really like the circular spine thing, doesn't seem like it fits with what you're going for, course that's just me. If you really wanna keep it, you can just keep playing around with the design till you find something that works.
But really, it all depends on your taste. That's pretty much my advice, another advice would be to look at the other quadrupeds of the series, I'm pretty sure theirs a few images of them in the net, and maybe in RPM's own database. (Something I should start doing before it's too late)