CZ 550's are heavy in most chamberings, but my FS in 9.3X62 is just right. It is a great shooter; the bolt was rough but smoothed up fairly quickly with use; I plan on keeping it forever. I had a CZ527 in .223 it was very smooth and fairly accurate, but I didn't shoot it very well offhand and I wanted a faster rifling twist, so I traded it.
I haven't shot a recent M70 but they feel nice and look good. I would make my choice depending on cartridge and the feel of the individual rifle.
