My thoughts, it opens up options for those that want to customize and doesn't put the responsibility on the RO's to know which parts are legal. Triggers, sights, hammers, internals...all fine. Must keep all safety features from stock gun (ie, keep your firing pin block if you don't have a Shadow).
I always had a hard time getting the DA reach on the 75 series, so I moved to the P-09. Now that I've got the option for a RRK trigger, I'm certain I'll be ordering one to try within the next couple months!