I've never seen it, but there are all sorts of rumors about Gabe/SI from various camps.
I found "Close Range Gunfighting" to be on par with most other "Level 2" courses.
I live about 30 miles from Shootrite and was considering taking training from Tiger McKee. At about the same time, I found out Gabe was going to be teaching about 45 miles away.
What swayed my decision was the material of the classes. I have a lot of prior experience, but at Shootrite I was going to have to start at the very bottom and take a succession of classes before I could get to any of the advanced level courses (BTW, I do understand some of the reasoning behind this [$$$]). I have read this is the case with other 'name' shooting schools.
Gabe was teaching Extreme Close-Range Gunfighting, one of his (at the time) most advanced level courses*. I simply emailed him my shooting experience to see if he thought I was OK. He told me "You should be fine in the class'. And I did pretty well.
I liked being able to start with SI on a level that was challenging rather than having to go through 'baby steps'.
IMO, Gabe's teaching style reminds me of listening to someone who has something really interesting to tell you and you want to listen. He was friendly and personable, but serious at the same time.
I have found this demeanor lacking in other instructors I've trained with.
*SI has since added some prerequisites for many of the Advanced courses.