Rega upgrade/tweak?

Have any of you out there tried the Express Machine Heavyweight Counterweight with your RB300's? I just installed one, so far it is only O.K. I believe there more hype that anything else. The improvements to the sound were a slight increase in treble and bass detail. A slight increase in dynamics. Now on some recordings the improvements were more noticeable than with others, but across the board I would say the improvments were marginal.

My analog system:
Rega P3
Shure V15VxMR
GSP Audio Gram amp 2SE

I am going to be buying a P3 soon and I was considering getting the heavywieght upgrade when I bought the table. So you feel that it is not worth it?

Have you tried turning the adjustment (I think it is called bias?) to three which disables the spring in the tonearm. Aparentlty that makes quite a difference, but the you need the heavywieght upgrade to be able to balance the arm.

What other eqiupment are you using. Phono stage amp speakers etc...

I am just trying to figure out if it is worth the extra money.
Thanks.

My phono stage is the GSP Audio Gram Amp 2SE.
Speakers: Snell EIII
Amp: McCormack DNA 0.5 Deluxe Edition
Linestage: McCormack Micro Line Drive /used passively
CD Player: Rega Research Planet /original

I am not about to mess with the arm in any other way. I am really not a tweaker. I got the Heavyweight for $80, so I figured what the hell. Is it worth it, sure, but it just didn't make as big of a difference as some people who I talked to said it would.