Rega RB301 VTA Adjustment other than standard?

It is to my understanding that from the factory REGA assumes one will use a REGA cartridge. I also understand that the tonearm is fixed to the base with 3 screws on 3 factory "spacers" already and with the stock felt mat the VTA is set for a REGA cartridge????? correct??? ok now my problem.

I am using a Ortofon M2Blue and have many records "standard" thickness, many 180g and a hand full of 200g.

I have messed around with removing the felt mat with the record on the glass platter just for kicks and YES I heard a big improvement.

With my new findings this past Friday night I ordered the 3 point spacer ring and a record puck.

NOW MY QUESTION!!

When I get the spacer do I remove the factory spacers?

How do I know which spacer setting will allow me to play my standard and 180g without a hassle?

What is a good starting point? (do I set it for standard weight records and get a thinner felt mat for when I play my 180g records?)

Any suggestions would be awesome.

Thanks,

Kev