Where to position a red dot sight

Given a choice of locations on the sight rib, what is the optimum location for a red dot sight, and why?

If the sight is mounted such that the weight is as far to the rear as possible, the felt weight of gun and sight is reduced.  I found this out with Matchdot II on Model 41.  I couldn't deal with the weight of the sight more or less centered over the barrel.  Additionally, the tech support person told me it is important how close the sight is to the support rings.  Apparently this affects reliability.

With a sight like the H-1 and H-2 Aimpoint, it's so light that the weight is not that important.  I tried mounting it in the rear slot, but then wondered if ejected shells and gas might damage the sight.  I just moved it to the middle slot, ahead of where shells are ejected.  There are other Aimpoint sights I don't have any experience with.  

There's also the front slot, but I can't see any benefit from using it.  It would move the weight even further forward, and would be farther away from the shooter's eye.

Any experienced feedback on where to position red dot sights?

put it where it balances best for you

Thanks, Chris.  Both the middle slot, and the slot closest to my eye feel good.  If there's no other reason to use one or the other, I'll try both, then decide.  It's so light, there is barely any noticeable balance change due to the weight.