Like the Federal Hydra Shok, Speer Gold Dot, and quite a few other "wonderbullets" the XTP bullet was developed as a result of the percieved failure of Winchester Silvertips in the FBI shootout in Miami.
I've tested and used XTPs for my home defense ammunition for quite a while (Although it's all theory, as I've not used a single round of XTP in ernest.). Factory XTP pistol ammunition is loaded to velocitys approaching Cor-Bon ammunition which is another plus in my book.
The TAP rifle ammunition is basically varmit ammunition under another name. They use hight velocities and bullets with a light jacket to prevent over penetration. Just another tool in your toolbox, to be used for a specific application. Invaluable under the proper circumstances, useless under others.