I have used kegs of AA2520 in the 308, 30-06 and .223. It is a fine powder.
My load in 308 was 168 SMK/Nosler 40.5 to 41.5 grs AA2520 LC cases, WLR. Now I use the CCI#34 in a M1a as the new brass WLR is thinner.
I used a lot a AA2520 in .223 with 69SMK/68 Hornady 25.0 gr AA2520 any case, WSR.
My main problem with Accurate Arms powders is that each lot very different. So, when I have purchased a keg, I have to go out and develop the load. I chronograph my loads, and the difference between lots, for the same velocity in 308, can be as much as a grain. That's a lot of powder, and on 100 F days, that is enough to blow primers.
Also, some of my 80's vintage lots had a lot of dust. So much dust that I had to use a QTIP swab ever ten rounds to clean out the powder measure horn. Or I would get bridging. With a ball powder!
However, when I develop a load, and get it right, the stuff shoots just great. It leaves more fouling than IMR 4895, which is my favorite medium capacity case rifle powder. Hard to say that makes any difference on target.
Vihtavuori 140 is an excellent powder. I prefer stick powders, which this is, and VV powders have been much more consistant lot to lot than AA powders. I use V V140 in my long range .223 ammunition and I know that only an improvement of my shooting skills can reduce the group.
But is it better?. You would have to define the characteristics you are looking for. It is certainly more expensive. That in my cheap book, is not better.
It has been a while since I used AA2520, but the attached target was fired from an M1a at a 100 yard Highpower match, during the prone rapid fire stage. The group was scored as 100-7X. The scorer might have been generous. Anyway, the stuff can shoot.