Cartridge for RB300 other things


i just purchased a used planar 3 w/rb300 arm(no mods) and would like some opinions about a suitable mm
cartridge (300-500 $'s). i currrently have an ortophon om30 and it's ok (a bit bright). also i'd like to replace the felt mat with either a ring-mat or audioquest sorbogel mat-what are the merits if any with either one of these and how can i adjust the vta for the mat & or cartridge. also if some one could pass along any other tweaks
that would improve this tt-thanks
vellum
I have the same setup and just purchased a Dynavector 10x4mkII. This is a great match. I also own the Benz Glider and feel the Dynavector is a better match for the Planar. Have not experimented with mats but I do know that the importer for Rega (lauerman imports) sells a VTA adjuster that fits on the bottom of the arm. So does VPI. If you go with the Dynavector which can be had from the Needle Doctor for $280 with trade you need one spacer under the arm and I have a feeling after hearing this cartridge you will not be taking it off the table anytime soon and dont need the VTA adjuster.
I think the above suggestion is a good one. My dealer recommended the Rega cartridges, and I know others use the Sumiko Blue Point special.
Rega recommends several different cartridges, including Dynavector, Grado, and Sumiko. I have a RB900 arm, and use Grado and Shure V15VxMR cartridges which both work well.
Why do so many people like the Blue Point? It's the worst. Go with the Dynavector 20 or Aurum Beta S