I've got a Caly 3 and have had no issues with the riveted construction. For some companies, the riveted build is a source of pride in the workmanship. I believe that one reason the Caly family is riveted is that the thin profile doesn't allow for screw-together construction, but I may be misremembering
. The blade has a screw, so it can be loosened or tightened to fit your likes. My Caly (like many others) came a bit gritty, but a quick flush with soapy water, rinse and dry had it working perfect. Keep in mind that out of the box the knife will likely be a bit tight, but with repeated use the parts will wear in a bit and loosen up a little, allowing for slicker blade deployment.
The decision between G-10 and CF is likely to be influenced by the blade steel you want: the ZDP blade comes in the CF handled knife while the G-10 handle is mated up with VG-10 steel. There is also a sprint run version with grey G-10 handles and Aogami Super Blue blade, if that is of any interest. It's a bit pricier and harder to find however. I don't think you can go wrong with any of the versions, however, as the Caly 3/3.5 is a fantastic knife.