Thermostats in general have been going to $hit the last few years. Most are a real crap shoot as to whether they will last past getting wet the first time. I had used the Mr Gasket high flow thermostats for years, they clearly flowed more. But the last few I have installed have been junk.

I now use the Stant Superstats. The opening is on the small size in my opinion so I add some holes to them to help with flow, but I haven't had any real problems with them............so far.