many thanks, travelinbeat, for all the response. (I couldn't find more specific info at manufacturers sites, just # gb and card makers that they've tested, without referring to class.) And, thanks to your suggestion, I browsed the section here on card media. Your comment was the most helpful one I found.
It seems reasonable, doesn't it, to go with thinking that if class 2 works on SD with Roland / Edirol it then it is likely the same would hold for using class 2 with microSD?