As far as I know its all. I have not worked on or read about the current generation but the first two for sure had the issue. There was not a problem the letting go the issue was when you removed them 9 times out of 10 the threads would come with. The few people I know that took them apart and thought they looked ok were doing it again. One guy found out when he started trying to torque them the other guy after a few weeks of running. With the proper timesert kit its a pretty easy job only thing you need thats not in the kit is a drill. I see the kits for sale all the time, often used once. The inserts are cheap. Its the step bits, special taps, and alignment plates that are expensive and because its aluminum they usually hold up pretty well. I dont think they are any more prone to head gasket failures than any other aluminum engine. Aluminum engines just dont put up with poor maintenance and overheating like cast iron did.
Call me TJ unless you would rather spell out 73eldoconvert
St.Paul/Mpls MN USA
73 Eldo convert... mostly stock w/Megasquirt TBI
93 Mustang convert, 96 Suburban 6.5 TD, 81 Riviera 5.7 diesel, 13 JettaSportWagon TDI