The sink is designed so you can apply 20mm reflectors directly to the stars.
The star is a MCPCB - a plastic reflector can't damage it. If you leave the legs on, most of the pressure will go to the sink anyway. If you clip the legs off, some pressure will go to the plastic retaining ring on the Luxeons - but judging by a 3x3 I'm evaluating now, that will have no effect on the emitters long-term.
If you remove the lens frequently, it's possible that you could scratch it, but if it's the stock polycarbonate lens, it's going to be scratched up in short order anyway just from day-to-day use.