One of my shooting buddies has a RRA varmint upper. Can't remember if it is 20" or 24". I have shot it side by side with my Bushie Varminter.
We each have the same glass (Leupold 6-18x40 target). His is on a Bushie DCM lower. We each shoot handloads. So far the Varminter is the accuracy champ. I have a number of half-inch 100 yd groups, a couple a bit better. The RRA has never done this well, although it is occasionally under MOA. I shoot mine with a Harris bipod; Doug uses a versapod (which I DON'T like). I wonder if the VersaPod is partially to blame, as it isn't as steady as the Harris bipod-at least with me behind it.
I also know that he has tried a lot more bullet/powder combos in search of an accurate load for the RRA. The Varminter liked my first attempts, especially 69gr BTHPM. Doug actually mentioned he might sell his RRA and get a Varminter upper. YMMV.
Oh yeah, the RRA upper is noticeably heavier than the Varminter. The fluting makes a lot of difference.