They hold but not of smooth as I would like. maybe then need a break in.
I added some grease but that seemed to make no difference.
I have used US made stuff that was smooth as silk. I don’t know if it is the bearings or the ground rods. I used the case hardened rod that says it is for linear. but maybe the chrome plated stuff is smoother. they do seem to work better if there is a lot of load on them. I get a bit of ripple in the spiral demo(going as fast I could get EMC to go). And the rods still flex a bit too. I wanted to fasten them in the center. but even after grinding a big notch I could not drill the stuff, maybe spot welding a screw might work. The rod with pre-drilled holes seems to cost a whole lot more.
but I think just one in the center would make a world of difference.