I have one here that I am planning to run on 5s in a 1/8 buggy. I am just waiting for the Hotwire to be released before installing it. I want to set a proper LVC for 5s lipo and the manual programing does not allow this. Hopefully the Hotwire is released soon. I have had one ordered and on backorder from tower for 6 weeks now.
I will for sure post my results when I get anything to report. I have been doing my own web scan for problems with the R1Pro and everything I see is from guys running 4 or 5 cell NiMH and very low turn motors. I really haven't seen any other complaints. I will be running a Hacker 10XL on 5s an I'll let you know how it works. I replaced the stock capacitor with a 1000mfd 35V cap to handle the higher voltage.
Here it is all wired and soldered up just waiting for the Hotwire so I can program it properly for my application.
I bought it used for a very nice price from a guy that had the same problem with the 5 NiMH cell oval carpet racing application with the ultra low turn motor. Unfortunately the guy had some pretty sad soldering skills and scared the front of the controller with the soldering iron. (but it shouldn't effect the function)