Ok, I understand now. Thanks for pointing out the difference.
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after reading your question again I realized you were asking about the Troy MRF (not the MRF-DI). The Troy MRF is a one piece rail and requires the removal of major components too install, whereas the DD Omega is a 2-piece, making installation a breeze. I run a Troy MRF-DI on my Colt 6920 and love it, it is very solid. If I wanted to spend a another $100 or so I would have certainly gone with the DD Omega.
Negative. The Troy MRF is a two piece, free float system which attaches to the barrel nut and butts up against the upper receiver. That is why the delta ring must be removed. You do not need to remove the barrel from the upper receiver or the FSB from the barrel, however. The MRF-DI is not a free float system and does not clamp to the barrel nut in the same manner as the MRF.
Thanks for the explanation guys.