Good lord, dude. I don’t mean to be a jerk, but this must be the fifth or sixth thread you’ve created over the past two months regarding hand guards and rail systems.
There is no such thing as a “regular rail” - they are all different.
The CASV is not everyone’s cup of tea. Mostly people are not fans of the weight and the inability to cowitness sites through a red dot optic without a low mount. Forget Eotech. Personally I like it.
I just finished a build using the CASV-M. The fit and finish is very nice. Like the others said, you either like it or you don’t. I really like mine. Most people are turned off by the inability to cowitness. However, I was not worried about that due to going the 1-4 variable route. For BUIS I use the Troy rear folding battle sight. For the front sight, I use the VLTOR Casv FS. I cannot comment on the weight comparison to the DD rails because I have no experience with them.