IMHO, this is money poorly spent and you would be better off upgrading the Rega P2 than plowing more money into a Shelter or Koetsu Black.
But to answer your question, a good friend of mine, who runs a Rega P5, upgraded to the 20XH from the 10X5 and had exactly the same reaction that you did. Not that the cartridge was bad, just that he did not think that it was much, if any, of an improvment. Funny enough, I had a 20Xl on loan, and it differs from the 20XH in having a line contact stylus, rather than the elliptical of the 20XH, and I thought it to be an excellent performer that was perhaps just a bit dymamically reigned in. YMMV and good luck with the hunt.
But to answer your question, a good friend of mine, who runs a Rega P5, upgraded to the 20XH from the 10X5 and had exactly the same reaction that you did. Not that the cartridge was bad, just that he did not think that it was much, if any, of an improvment. Funny enough, I had a 20Xl on loan, and it differs from the 20XH in having a line contact stylus, rather than the elliptical of the 20XH, and I thought it to be an excellent performer that was perhaps just a bit dymamically reigned in. YMMV and good luck with the hunt.

