I'm willing to bet that the percentage of PNMs who were totally cut in early rounds is far higher than those who went bidless after Pref. Over the years I've heard of very few PNMs who went bidless after Pref, unless they didn't maximize their options. But I've heard of tons who didn't receive any invites in an earlier round and even more who voluntarily withdrew because they weren't happy with the invites they received.
As for grades, we start off using the GPA a PNM reports on her registration application. We then compare that to the GPA reported on any Recs we receive. Finally after registration is closed the University provides us with list of the actual GPAs. I've seen PNMs flat out lie or "round" up. I'm sorry but a 2.7 cannot be rounded up to a 3.0.

I guess they don't realize we actually check these out. Lying about something so important says a lot about one's character.