A: Yes, in June 2004.
A: Several reasons. The main motivation was that my wife and I got tired of having people assume that we were not married because we had different last names. Even though being married with different last names is now a common practice the default assumption in our society still seems to be that a couple with different last names is living in sin. (Of course, we've got nothing against living in sin, but it's annoying to have people assume it nonetheless.)
Q: Why Garret?
A: It's a long, convoluted story. We weren't really fond of either one of our existing last names. My wife's former last name was "Trowbridge", which wasn't really her name at all, but her previous husband's name. I've never been very fond of the name "Gat". It's too terse, and requires constant explaining. Gat is also not a family name that goes back generations either. It is a name that my father chose when he changed his name back in the day. His motivations were also purely pragmatic, so changing names is as long-standing a tradition as any in my family.
So we decided to choose a new name tabula rasa. We took my name, Gat, merged it with her birth name, Rodgers, and came up with Ga-Rodge, or garage, which in England is a Garret. (Update: it turns out that a garret is actually more like an attic than a garage. Oh well.)
The reason for "Ron" is that I decided that as long as I was going to go through the trouble of changing my name at all I wanted to have one that didn't require me to explain and spell it all the time. "Ron" sounds pretty much like "Erann" when you say it fast. Also, I realized recently that in English, names with the accent on the second syllable are almost invariably female names (e.g. MiCHELLE, DeNISE, MaRIE), which is probably why people were forever trying to call me Aaron. Going with "Ron" solves all those problems at a stroke.
(Update: it turns out that there are some English male names with the accent on the second syllable, e.g. Jerome and Bernard. But these seem to be very much the exception.)
Q: "Ron" sounds so weird to me. Do you mind if I keep calling you Erann?
A: Not at all, though I've been "Ron Garret" for nearly ten years now and I'm starting to get pretty used to it. I have really found it very liberating to have a more ordinary-sounding name, especially when I meet new people.