When do you know....

When you mount your Van den Hul Colibiri on your SME M2-9R 

In a way, it also depends on other things like the turntable and phono amp, device matching, power supply, rack or turntable support. Your Rega RB2000 is a good tonearm and capable of working well with a $4000 cartridge.

Hard to know until you get there...and by 'there' I mean find an arm + cart match that does allow it all to happen ;)

I wouldn't personally consider carts known to work best on high mass &\or steel arms in this case. Maybe that's stating the obvious tho...