I'm familiar with Thomson but not their AccuGlide (THK like) rails. Are they any good? I'm considering some for my Z axis to traverse on, about 25". should I just stick to the Thomson rod and bearings I'm used to? The AccuGlide would sure mount nice on my gantry bridge.

Thomson makes good stuff. I'm not sure why they don't seem to have as much presence on Ebay (which is probably a good indicator of market share), but I'm sure they are more expensive.

as with any rails like that, you want to make sure they have 4 rows of bearings. A lot of precision machinery can do with 2 rows of bearings, but it's not quite stiff enough for cnc machines. As with anything, if it's cheap enough, ignore the rules and try it. My only complaint about Thomson is that they have too many different designs. I bought some rail really cheap, but I can't seem to find any matching parts.