Got some questions about the OKO, I went through alot of previous threads and alot of people say their not as rugged as aimpoints or eotechs. Has anyone had any issues with their OKO's? How do they stand up to shock or moisture?

I've had an OKO on one of my AR's and on two of my Glocks for about a year.  I don't bang it around or drop it, but it stands up to a lot of recoil (10mm and .40cal) with no problems.  You can buy the metal cover that protects the sight if you're concerned about rough use.

As far as moisture is concerned, CavArms used to have a picture of an OKO sitting on the bottom of an aquarium with the red dot shining bright.  

No, they're not, but they're not as much either.

No issues, but I recommend the SC-3/SC-4 covers.

My OKO broke at the mount were it clamps on to the flattop. I did not drop it or anything.

I really like the sight but it is definately not as rugged as the Eotech or Aimpoint.

I believe the sight itself would hold up very well if the mounts were designed better.

Personally I would reserve an OKO for a lightwieght AR.

For building a CQB or more "battle" ready AR, I'd go with (and did) the Eotech.

OKO $200.00, SC3 cover, $65.00.
You can get a Eotech 511 for $270.00 shipped.