I use the R9, it's a very good driver! I have to admit though, there are about 3 or 4 drives where the R11 does make a big difference. Distance wise, there is not much if anything in it at all.
I would say, get the R9, you won't be sorry. I saw that you are only 3 level away from 88, but that could be a few weeks.
I have just reached lvl 88 and am getting the R11 (just saving my pocket money :-))
GL