Do you use a wool record mat? Do you upgrade?

I have been in this hobby for many decades, when I hear something said to me from a professional at a store that doesn't make sense to me, I ask YOU the people in this hobby. Regarding REGA turntables do you keep the wooly mat they give you? Do you NOT upgrade the bearing system? and Isolate the table with a platform? Is it BAD OMEN to upgrade the belt, or change the platter from glass to acrylic or delrin? I would think anything that makes your table sound better for a little money would be a welcome investment. After saying all this. I use a Acrylic platter with no mat and a JA Mitchel record clamp on my REGA P3/24 with a Mapleshade ISO platform sitting on Iso blocks. The P3/24 is now dead quiet and with the bearing change (steel ball w/brass post to CZ ball w/solid steel spindle with sapphire thrust plate) It spins effortlessly and has raised the level of this table considerably. Why are some dealers so opposed to tweaks or 3rd party upgrades? My local dealer has lost me as a customer because of their ridged beliefs!