I've since signed up with Virgin on the $10 plan. As you pointed out, it is $10 plus .10 cents for every minute you use. For a light talker, it's pretty cheap for me. I only use about an hour a month, so I'm looking at $16 per month + taxes. That's much less than my current $25 plan that costs near $40 once all the extra fees are added.
I did miss the part where you mentioned Virgin has no US roaming. I wish I didn't miss that because I realized this after I had signed up... Ugh.. I do travel in the US now and then and that might be a problem. (I'm going to Hawaii in February).
On Rogers GSM phones... I don't know how it is now, but 5 years ago I drove from Toronto to Winnipeg through the U.S. with a Roger's phone. Once I got out of Detroit I had 'No Service' for most of the way through Ohio and Indiana. None of the many cell towers I saw along the way supported GSM. I wasn't impressed. It might be different now, but then, I only got coverage near major centers.