I had to have the FNH. I have seen the CMMG for about half the cost. CMMG has extended PS90 rails as well. I have also seen some nylon rails for less still yet. The FNH rail DID mount easily, and came with nice hardware. If budget is an issue, you might consider options. After all. its just a bar with simple machining.
Pros: Works as described.
Cons: $$$
This review was written in the old system and had content requirements that are different than reviews written today.