They work fine. I use them on a G35 and G27, and 5 friends use them on40 cal GLOCKs. No issues with WWB or similar ammo, some issues on under-powered reloads (bunny fart loads). All told, I have 3 years of experience with mine and will whole-heartedly recommend Lone Wolf conversion barrels to all interested parties.
You don't need to change out any internal parts--no ejector, no extractor, and you CAN use a .40 cal magazine if you don't want to buy 9mm mags. I use 9mm mags.
They work!
HK Dan