I have been working the GMC booth for the past 4 years now at the American Quarter Horse Association World Congress. This year I have not had one person come up to me and even mention any issues with the aluminum heads.
Funny, this used to be the main focus of my discussions just a couple years ago. I have herd a few injector stories though. The vast majority of the people I talk to these days, own one, have driven one or know someone who has one and they are very happy with them.

P.S.
Kudos