I own a DD Omega 9 inch rail that I installed on a BCM 16inch middy for similar reasons to you OP. Not wanting to muck up the upper.
First, I haven't used the Centurion rail, but I do have the opinion that the lock up is probably more solid. That said, I have not had any issue with the DD rail loosening up over the two years I have had. With that out of the way, the DD rail installed pretty easily, I think I used all off three tools, an allen head wrench, a flat head screw driver, and a old ACOG mount. Probably spent more time lining the top rail up than actually installing it and it works as advertised. Was it my first choice of rails? No, but got it silly cheap, like $160 on clearance from Rainier I think and since that rifle was at the time my pseudo DMR think a freefloated rail made sense. Currently though, it has an M600U with an SR07 pressure switch and a BCM vg with some larue index clips. The light and VG I could have kept with by using the MOE handguard that I had on there and I had printed more than respectable groups with that, the desire, that never happened, was to have the rail to mount a bipod. The DD rail is also rather, girthy. It isn't a rail you are going to wrap your fingers all the way around unless you are some freak of nature.
If you know what you are wanting to do with the rifle then grab the rail that you want. If you don't know, I'd honestly consider just slapping on a set of regular handguards or an MOE handguard and figuring out what you want to do with the rifle. Sometimes, I think the problem with ARs is that we have entirely too damn many options.
"Some days you eat the bacon, and other days the bacon eats you." SeriousStudent
"Don't complain when after killing scores of women and children in a mall, a group of well armed men who train to shoot people like you in the face show up to say hello." WillBrink