Have 4X G2 k320's and 2X P400. I run diesel with kt oil in all of them. no experince with the P300's.
No issues with either of them.

I prefer KT mainly because of the fast spoolup (idle to full throttle) - 3 seconds on my KT320's. Also some added benefits of the auto restart feature (comes in real handy when stressing airframes with tons of aerobatics on low fuel), simple to understand GSU and easy adjustments. KT GSU graphs are also nice. Is P400 spoolup (idle to full throttle) is 8 seconds - ugg!