Meh, a bit disappointing, but then again I've been playing legion since last year, so all this stuff is all to familiar.Hey, everyone else too, what a coincidence!
Ok, snark aside, there's a conquest for a solo 75 GR, then yes beyond that it's just more exp/gold/magic find. I'd personally say it's noticeable and worth finding the sweet spot between easy-steamroll and takes-fourteen-minutes, but overall it's going to be purely psychological on your part. Whatever you find fun in balancing the time spent, challenge, and rainbow explosion when you kill the RG.