IOR M2 Pros: Fog/shock/waterproof, great optics, illuminated reticle/stadia lines, fine BDC, clear knob markings, and excellent value. I like the removeable eyepiece.
IOR M2 Cons: Some scopes use 19" widths, whjicjh I prefer as you can't always expect your Bad Guy to be fully standing. I honestly can't find any glaring faults with this scope! Perhaps service support may someday be lacking, but that's assuming the scope fails - which seems very unlikely. I'd like replaceable BDC cams, but that's getting pretty picky.
Final word on the IOR M2: I think the M2 is the ideal scope for most battle rifles.