New they do run stiff. Load them down and the motion will smooth out. Much of the sticky feel is likely the wipers and/or side seals.
I am sure they will be OK. I have torn down blocks that were so packed with MDF dust that I was amazed they even moved at all, but they moved fine.
And, yes - they do run louder than one would expect. Grease will quiet them down a little, but not by very much.
Just don't lube them with anything but a light lithium grease or an oil - do not use just whatever you have laying around - get the right stuff if you are inclined to lube them up! For a dusty environment, I would suggest using an oil feed system set up on a timer - give them a shot of go-juice every once in a while. Grease is a dust magnet.