Nervous Meter says Moderate

The parents meet Cliff for the first time Saturday. I am kind of hoping they don't take another 5 years to warm up to him like with previous versions. And by they, I mean dad.
I should take bets on how long it takes. Figuring out the odds for this stuff can't be that hard.
+'s
workaholic
treats me well
suitable age
college-educated (same school even!)
stable (i.e. not the depressed, artistic type)
polite
parents still together (it matters to them)
daughter nearing age 30 (not that this is really a plus, but it does soften the edges doesn't it :)
-'s
white
male
Hmm...

How it works
My parents never really warmed up to any of my girlfriends (not that I had many), but the second they met my love, they loved her. I think parents just have something akin to spidey sense for non-the-ones. While you're busy being infatuated and happy, their spidey sense goes off and you can never figure out why they aren't warming up and seeing how marvelous the person is until Was-the-one reveals their true colors. I think it may be one of the last re-affirmations that oh yeah, my parents really do know what's best for me. Disclaimer: A-hole parents have no spidey sense.
P.S. Having both people in a relationship with both parents still married does matter if you look at statistics. It doesn't matter when you look at individual cases. Your parents aren't crazy to look to that as an indicator or wish it for you.

Nice theory
I like your idea of the spidey-sense. I now have visions of parents standing in the kitchen, getting deep senses of dread without knowing why, and then seconds later the boyfriend walking in to introduce himself.
However, I didn't experience this with my parents. Both of my parents liked all of my serious GFs. Sorry Nat, I don't mean for you to feel un-special.

How it works 2
It doesn't hurt to be overly confident with your parents about how much they are going to love someone. If you are super confident, it bolsters their outlook. If you go around saying so-in-so is really nice, don't talk about this, or don't mention this, or showing any general signs of reservation or hesitation, I think that trips their spidey sense.
Best of luck!

Funny
I think you are totally right about the whole confidence thing with this type of situation.
It is the completely opposite of movie expectations though. If people keep telling me how great a movie is, by the time I see it I'm often really disappointed because it couldn't possible live up to the hype.
I bet it will be fine
You are nearing optimal grand baby making age. My guess is you could bring home a bum and they would love him.