That's what I was told too. I seen plenty of others using it also. That still didn't make it the "correct choice" for me.
I didn't have caps for the rail mounting bolts & likely that is where at least some of the contamination entered the bearings.
I have recently had a close up look at a large Dynatorch. They use recirculating ball linear rail on their gantry. Holes are capped & the rail is directly on top of the gantry.
All I can say is: It hasn't worked well for me.
Neil
If it works.....Don't fix it!