Well the latest tale of this story is that after I had to pay a portion of the valve job, I picked it up and within a couple of days of city driving short distances, my full tank of premium was down to empty, and the check engine light has come back on. It is not running as rough, but still seems to hesitate and is not as rock solid as when I originally brought it to them.
The supposed collapsed lifter was not noticeable, and ever since they did that job (but failed to see the carbon buildup on the valves) it has run much worse.
At this point I have lost faith in the integrity of this vehicle, and went from really enjoying it, to not trusting I can go on a trip outside of my city and not worry about having a problem.
I talked to a friend who was a GM of a car dealership years ago, and he said to requested a special dispensation from Cadillac/GM to have my warranty extended to 100K for the drive train. However my issue was not the mileage running out (currently 68K) but the time ran out last year in between the 3rd & 4th return for the same problem. Hence they "did me a favor on the GM calculator only having to pay 40%" of the valve job.
I really don't want the hassle, time and expense of taking them to court, as I am not a litigious guy. Additionally, even if I were to prevail, all I'd win is my money back and them having to continue to fix my engine for free. Or at least that is all I assume, as punitive damages are not common in small claims court.
Heck I'd gladly just swap it out for another SUV, but I doubt the dealer will entertain such a remedy.
Aside from being angry, what is worse is not really knowing what to do at this point.