I’ve ridden the RR for two seasons now and really like the hand positions. (For me it was more about comfort than aero, but I got both). I had posted about them in [this thread] (Handlebars - Narrow or Aero?) (my post is the last one on Jan 19 of this year).
The bar is a pain to route internally, either hydro hoses or shift cables/wires. I did run internally after a lot of cursing; when I moved the bars to my new bike I didn’t even give internal a thought and run hoses both externally and I think it looks and works fine. Despite being a long-time dedicated Campy guy, my Trek Domane+ has Di2 12 which has wireless shift levers. Pretty sweet for setup, and I have to admit that this first foray into electronic shifting and the Shimano hoods has gone extremely well – but not so we’ll that I’d change my Chorus mechanical hydros on my Alliance to Shimano:))
I just ordered a set of RRs in 40 after having ridden 42s for a long time. I think the slightly narrower hoods will better match my shoulder and I’ll still have 42 measurement on the drops.