I own a Guru and a Guru Mighty. However, the Tremendous Pearl is not out at this time. So, take my comparison with a grain salt...
Based upon what I know and have seen out of all of the Guru balls, the Tremendous Pearl looks like it will be the weakest of the series of Guru's. Although the core is strong, the cover looks to be the weakest of the bunch.
As you will remember, the Guru Mighty was a hybrid ball that has somewhat of a matte finish out of the box. The Guru Limited would be closer to the Tr.Pearl in terms of cover, yet the Limited would still be stronger.
The Mighty is not a weak ball by no stretch of the imagination if you use it on the proper condition. Bottom line is that is needs oil to perform well. In my opinion, it was one of the best hybrid's ever made. Period.
Based upon the videos of the Tr.Pearl, it looks to be more skid-flippy. The Limited was that, but very quick on the back end. My best buddy has a Limited and in his hand, he can bring it back from anywhere if there is a dry board on the lane. The Tr.Pearl does not appear to be as quick. However, as you know, the core is where it's at! LOL.
If you can find a new Guru Mighty, buy it without hesitation. However, if you're looking for skid-flip try the Limited or the new pearl. Radical's ball chart should help you, too.
I'll probably be getting the new Katana early next year. It reminds me of the Gusto in terms of the color, but it looks to be even stronger than what the Gusto was. Good luck!
Peace!