it would probably depend more on what switches you're planning on using.
I do know, I'm planning to use Kailh BOX, either Pink or Pale Blue (I have the pinks already but I'm having second thoughts). The spec sheets on NovelKeys show a tolerance of 0.05 mm on them.
there are some models from some brands that have a much tighter fit than cherry.
This is where I get confused. You say that Cherry have a loose fit, but the Cherry MX datasheet on SparkFun specifies the same tolerance (but in inches as 0.002").
it shouldn't be a problem, because even the MX/ALPS cutout (supporting switchtop opening) will hold MX switches just fine, which is a lot less contact between the housing and the plate than a standard MX cutout without cutouts for switchtop opening.
Are you saying that cutting to 0.005" tolerances won't be a problem for a standard MX cutout, based on the fact that even the combined MX/ALPS cutout works and it's way wider in the X dimension?
I am planning on using what swillkb calls the "MX Openable Cutout"