Hi, Tom.
If you are pleased with your improvisational skills, there's no need to buy any book. If you're not, then I guess you should try and figure out where the problem lies. If it's creating melody, then
PT will help a lot. If you prefer to hear scales, then stick with scales and try and figure out how to juggle them around in a real piece of music, especially one that isn't strictly diatonic where (I guess) you need to keep switching from one to another.
The PT 'trick' is really just a very succinct way of seeing the whole fretboard as a unit, a kind of 'bottom-line' map. You can measure anything at all with it, including all scales and boxes and modes.