In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
There are variances in all copper tube. The specificatiosn give a minimum and a maximum. Some manufactures make to the minimum, some to the max, and some between the ranges. These are set by ASTM standards that all tube must meet. There is even a standard for PEX tube... and yes I have seen tube within spec that slid easily in CFin.
Anyway, I regress. My point is that all fitting must be able to work on the minimum and the max OD and ID of the copper. With solder we fill in the joing so the solder fitting people have it relatively easy. The Oring people have their work cut out for them... but I have never seen a leaking Nibco or Sharkbite fitting.... but I am sure it will be coming :-)