I've found Spyderco's and Byrd's (a less expensive subsidiary of Spyderco) to be equally as easy to use right or left handed. They have holes rather than studs for opening, thus ambidextrous. They are lockbacks, so inherently ambidextrous to close as well, although I'd never try to close a lockback one-handed myself. I don't like closing any folder one-handed for that matter.

I'm sure the mini-Grips are fine knives too. But just in this short thread I see there are a couple of people who have had trouble with them. So the problems can't be that rare if they've been seen more than once in such a small sample of people.