From someone who owns both a Remington full-bore varmint (22-250 700 SPS), and a CZ 527 in .221 FB and same Rem. factory ammo:
I agree 100% with GB. Took words right out of my "mouth" re. the Remington.
Absolutely love the CZ, a great shooter with trigger in either position. Am tempted to agree about it running with the big boys with far less weight, etc.; it handles like a rimfire. However, it does have its limits and wouldn't use it for one-shot kills on a regular basis on my Eastern bean-fed groundhogs much past 275 yards on a regular basis in the .221.
Don't know of any other brand of heavy-barreled .221 for a comparison to the CZ sporter to really prove our hunch. At this point, if I could keep only 2 of my varmint rifles, it'd be these two. If only one, (God forbid), the practical choice woud be the 22-250 Remington.