eotechs are a zero magnification holographic projection sight. The reason they arent as cheap as a red dot it that red dot sights a a general rule only hold zero at a certain position realtive to your eye. Since a red dot is a reflected light it is stationary in the sight picture, the holographic sights however are able to hold their zero no matter what. I.E.- take a mirror and shine a laser at that mirror, if you are holding that laser and move your body, the reflection moves. however, if you use a projector and project the image onto the wall, the image will not move if you move your body. This is greatly simplified you understand, but it communicates the point. While red dot sights may be "mostly" paralax free, a holographic sight eliminates the issue of paralax and superimposes an image at a "virtual" 50 yards downrange, allowing the shooter an uninhibited viewing/aiming system. At least thats true of Electro-Optics Technologies, or eotech for short. These sights are incredible, and for a red dot or "reflex" sight to achieve this level of accuracy takes a great deal of precision in the manufacturing of lenses and equipment, which is why Aimpoints are so expensive. But if you are in that price range, either will do fine, Ive shot Aimpoints and Eotechs and I have an eotech on my ar. Its mostly preference, I just like the 1moa/65moa circle in the eotech. Insight Tech also makes a wicked red dot sight called the Integrated Sighting Module.
http://www.insighttechnology.com/InsightAimandIllum.html. I have a buddy who shoots one and loves it, but they are far more expensive if you opt for the IR package. Optics depend soley on mission requirements, and thats to say, what are you going to do with it. High dollar optics are built to endure the stresses that the grunts put on them. Thats the proving ground, and I promise, Marine grunts can break anything...
