Rega says not to use clamps with their tables, one of the reasons being because of the extra weight. My dealer has done several tests with customers who all thought it sounded better without the clamp, and that has been my experience as well.
Record Clam, yes or no
I have a Rega P5 and have replaced the glass platter with a Groovetracer acrylic platter and sub. I used a HRS record clamp and loved it with the glass platter, I chose it because of the rubber undercoating and the nice fit around the spindle, plus it is the best clam I have used. Since I replaced the glass platter, I find I like the sound better without any clamp, at all. I found the damping from the clamp too much, almost flat. So now I do not use any clamp and really enjoy the sound. Has anyone else had a similar experience?