Just to clarify, are you talking about XZ plates? or YZ plates?
12mm MDF YZ plates are the standard, and what came directly from the V1 shop. I haven’t had any problems with 12mm MDF YZ plates, and I’m not aware of anybody else that has either.
If you are intending to replace the YZ plates with aluminum plates later, 12mm MDF will work, and be a lot easier on you than having to modify the build, just to replace it later anyway.
I have painted MDF, and have had no problems with cuts, or humidity, etc with them
For XZ plates (blue in the above picture), 3D printing them works fine