C. Diver,
The Center X ammo is very good if you have the right lot for your rifle. I sent a rifle off to the Lapua test range in Mesa, Arizona.
They tested a number of different lots in my rifle and some shot badly and a couple shot well. I bought a one brick short of two cases of the good stuff. The ammo was tested in my customized 10/22 that I use to shoot Automatic Benchrest and I found that it shot great in my bolt rifle. In the only 50/50 match, so far, I shot a 249 and two well into the 240's here in San Angelo. I did use wind flags.
The point I am trying to make is that any premium brand of .22 RF will vary lot to lot. Another funny thing that I have found is that a good lot of ammo will shoot good in other good rifles. You should test several different lots of the ammo and if you find a great lot, you should buy all that you can afford.
Concho Bill