I've upgraded all the non-battle pets that I could. It may not change your pet score (at least not now), but those pets still show up as rare in your pet journal and when you've summoned it, their names will be in blue instead of green. That's good enough for me.
I've got a question, though:
Amadia wrote:I've upgraded my ...Guild Page, Guild Herald...
You were able to upgrade your page and herald? Did you do this in 5.2? I tried to upgrade mine a month or so ago, but it wouldn't take.