I didn't realize the P10 has a different mat than the P8. Maybe the P10 platter is thicker. I got the P8 close to when it first came out and the P10 was still a confirmed rumor (so I never saw one) with no release date in sight. Rega sells other color wool mats and says they fit all Rega tables. Either they forgot about the P10, or they think a 1/2mm difference is insignificant.
The cool thing about the Hexmat looks is when a record is playing how it looks like the record is floating above the platter. When it is on the platter with no record on it, it certainly looks different. I could take or leave that, but the look while spinning I like very much. If I had a white platter, I might think differently.
Anyhow from a purely sound (not functionality) standpoint, it is tough to tell the difference between the Rega, Herbie's and Hexmats, which is why I watched the Audiophile Man's review of the Hexmat, but as usual, he basically said you get what you pay for and didn't say which was the best bang for the buck, but since the Hexmat was most expensive, he unsurprisingly liked it the best, by a good bit.