So far I've got 60K miles on my MLS with no issues or signs of an issue. I was able to compensate in the height loss of the machining operations with the gasket by ordering it to a prescribed thickness. With the length of this aluminum head, I think the shear forces on the gasket exceed what a composite gasket can handle in any kind of overheat situation. I don't intend to intentionally overheat it, but if it does happen, I think the MLS stands a better chance of surviving it, but that's all opinion.I made a decision to use an OEM style composite gasket for reliability as the purpose of my build is for stock longevity with some mild improvements that should improve low end and overall driveability. MLS gives you the advantage of different compression ratios. Decking the block and head is to have a perfectly flat surface for good sealing. MLS requires a certain type of surfacing to seal. I’ve personally yet to meet anyone that said they ran an aftermarket MLS and went 300k miles on it without a headgasket failure. Locally where I live the MLS failures on engines in general far exceed composite. Blocks with floating bores are especially susceptible. At least the 1fz isn’t. It’s just something I didn’t want to chance on this build. If I was building a race motor with frequent rebuilds I think it would be fun to try.