Nah, the RT615 aren't an R-Comp, i think the R comps generally have a wear rating of <100. I think these have a wear rating of 180. So they aren't as soft, however share a few of the other traits usually found in semislicks, being the stick sidewalls & large block area (added stiffness and dry handling ability, turns to poo poo in the wet though).
I'll probably move to an R-Comp like the Bridgestone RE55 after these wear out. I couldn't justify tyres that'd only last me 5000km or so (gentle street driving) when my clutch alone requires over 2000km of breakin before it can be harrassed too much. No use having absolutely awesome tyres if you can't use the car to that potential anyway. These should last at least 10000km (and up to 20000 dependant on driving habits) whilst still provided outstanding grip. Good for the weekend sprints. I hear that in long sessions though they can overheat and start to get a bit greasy. Considering your normal sprint days are only several laps, shouldn't have many issues though.