I'd like to read what Phil has to say.
Quite honestly, neither the Primo nor Guru Master have been must-haves among my tournament pieces. I know of a bowler in my area who has done well with both, as well as the Guru Mighty. (Personally, I've seen scoring success with the Untamed and Reax Gusto so far this year.)
Who knows? Maybe the Guru Supreme and Ridiculous will be.