i have OKO's and EOTechs....i like both. i actually prefer the OKO over the Aimpoint, although i would give the Aimpoint the edge in overall durability, simply due to the fact that it has flip covers and a heavy coating.
However, i hate "tube" designs, and can not use an Aimpoint effectively (that's just ME though). between OKO and Eotech i do seem to shoot better with an EO past 100 yards, but i love having the OKO on my CQB-type guns (Remington 870 with SST-870 adapter and 9mm AR15).
other factors: yes, the metal shroud for an OKO costs more, but so does a mount for an Aimpoint! battery life is almost a Non-issue with the OKO...1500+ hours.
just my random thoughts.....