4 meters of Misumi 2020 is $23… Yeah, conduit is even cheaper, but we’re talking about a pretty minor part of the total build cost, for some substantial advantages. V-wheels on extrusion will be even cheaper than conduit and linear rods. I am 100% in favor of conduit frames where extrusions are hard to get, but in the US, extrusions are a no-brainier.
What is the wearing rate of plastic wheels? I’ve read complains about igus drylin linear bearings wearing too fast due to the amount of movement they get in a XY configuration of a corexy (z would be acceptable). And even Igus doesn’t claim that its plastic bearings are intended for precision linear movement…
Delrin wheels with ball bearings don’t wear at any meaningful rate on aluminum (within a typical printer 1,000-10,000 hour life anyway). It’s primarily rolling contact. You do see some “bedding in” effects if you run V-wheels on T-slot profile instead of V-slot, but once the grooves are set, they basically stop wearing.