I have seen this pop up throughout this forum...has anybody realized any performance improvements with this system? What is the disadvantage of using it? Thanks.

Just don't over oil it when it comes time to clean. Almost everybody over oils it by default I'm told.

Yes, many people over oil it, I have replaced many Mass Air Flow sensors for that. The oil will coat the sensor and kill it.

Most "improvements" I have read are purely subjective and none have dyno numbers to back them up. Be sure to oil them just right or you will risk clogging up your MAF. Dealers are told to look out for over oiled reusable air filters and not to do warranty work on cars that have oily films.

When it's time to replace mine I may change to K&N. The price for GM OE and K&N are close.

I don't think a drop in filter will add more than a few hp, IMHO.
All K&N filters have come pre oiled from the factory for the last few years.
;)
I just installed today the K&N FIPK for the car, it feels stronger in the upper rpm range, and you can hear it pulling in air.
B)
Next stop Sunday, cam/heads!
:D