I was satisfied with the MCU for about a year and a half too... then I started working on the body and frame and found my satisfaction had turned to 'another hard lesson learned'.
I'm just reporting my experience with Chassi Saver. It called for an "S-88" activator/hardner making it a 2 PART when I used it in 2010. Maybe with no S-88 is stays soft but that's not how it was advertised to be used to me.

a year later, it peeled in sheets whenever I hit it with air pressure except where I put it over rust. WORKS GREAT OVER RUST!
Where it held 'as advertised' it looked great unless I tried to sand it. Sands like concrete. Once the outer layer was scuffed open it was porous and very difficult to remove and nigh impossible to feather. NOT a problem with Epoxy primer. I use it as my build coat it sand so good. (SPI brand)

Since switching over to epoxy primer I have seen the difference first hand in adhesion and flexibility of the two cured products.
I want something that moves with the metals expansion and contraction and is more chip resistant... thus the switch in my case.
To each his/her own.
But those who come looking for the industries best practices will not find much (if any) MCU products being used by top end professional shops (meaning if it fails they stand behind it and fix it) for restoration. They are just not worth the risk...

I am NOT a high end shop... I just like to use the best stuff if/when I can and also educate myself regarding products pro's stay away from. It's not trying to convince anyone to use a certain product, but I am trying to warn others...

Give me ambiguity
or give me something else