I have made as clear as I know how many times what the reasons are that I prefer the SIR's. One thing that I didn't mention is that there are ways that alow the flashlights, etc. to be attached directly to the side of the SIR hand guards using the track the selective rails do. Doing it this way puts the attachment closer to the side of the hand guard reach than attaching to any dovetail, almost built in.
There are other devices coming that will also plug into the sockets along the side upper portion of the SIR top, that go to a wiring harnes that also will be putting push buttons in the lower polymer hand guard. So I'd say if you want provisions ready made for the future of things to come, go with the SIR, instead of plain alum rails and thats al you get. That's one of the reasons that the cooling ability was built in, electronic's of the future.
Good shootin, Jack