I have a 30 inch Rotatrim and routinely cut matboard with it.
Occasionally I get some extra dense matboard that tries to lift the cutter.
When that happens, I purposly push straight down on the cutter a bit harder to prevent upward bowing of the 34" long rods.
My unit's probably 10+ years old and used mercilessly.
Fiber paper, RC paper, interleaving tissue, matboard.
Nary a nick in the blade.
Always a perfect cut..
Trim 1/64" off ???