The only 2 times I heard he mention it is on the DR String ad on YouTube and his instructional DVD. For standard D, 11-50. For Drop C, 10-56. I just go with the TiteFit, if he like it, he'll stick with it instead using 2 different one.
I read this from their website so maybe "round" is where the R come from, just guessing.
"electric guitar strings are designed with pure nickel wrap wire, round wound upon round core"
Yeah, it's personal taste. I prefer low action and a little slack in the string, make annoying string buzz when not plug in amp but doesn't matter of course.