I have a little experience on dust issues on round quides.
I would start from two ideas:
* Prevent excessive fallout on quide rods, a little shield on top, maybe an ash vacumcleaner or something (you don't want to set shopvack on fire).
* keep quides dry and clean.
We had one system with plenty of abrassive dust, few hardened quide rods and plenty of ball bearing bushes. When lubricated regularry, the bushes wore out no time. They lasted about as long if they were never lubricated or lubricated with "dry" lubricant. But they life was varied even more (like factor of five) depending how often the ways were cleaned on shopvack. Claning with pressurized air was worse than no cleaning at all!
It's rally hard to prevent ingress of fine dust. IMHO non pressurized belows are not worth of it. If you get any dust/grinding paste in, it's really hard to get it out.
Commercial manual grinders seem to trust on design, that minimizes dust fall out on quides. Labyrinth seals with pressurized air purge are pretty involved.
On that type of machine I would put some shields and some wipers/lipseals to prevent any bigger that rodent size particled entering into linear bearings.
Pekka