I have 2 of the Micros (
http://www.aimpoint.com/products/all-products/product-singleview/product/micro-h-1/ ), one on my .35 Rem in a Scout mount and the other on a Rifled 20ga Double Barrel, also mounted out front.
Also have 2 Bushnell Red Dots and 2 old Tasco Pro Points. These are mounted on a 14 inch TC Contender .44 mag, a O/U 45-70 and Louann's H&R .243 single shot and also on the rifled 20 ga barrel that fits the same frame.
For close in hunting they are perfect and we've had only a issue or two, both times with the Bushnell ( Lifetime Warrenty so they fixed them! ).
The ones in the forward mount are very fast and as I was taught to shoot with both eyes open it is very natural. The dot seems to just hover out there.
And what you can do with one is amazing. I've shot deer and hogs from the stand one handed with my arm extended and the gun resting on a leg or a limb, both times with the .35 Rem. All you have to do is have the dot wherever you want it to hit......no need to worry about eye relief or whether the thing is centered.
But I will say that what you mention is true......no light gathering qualities. You lose a few minutes.......which I find to be more than made up for with all the other qualities.
Besides that, as we shoot CLOSE only I can't really say I have ever had to let one walk during legal time because I could not put the dot on him.
Lot's of new offerings out there besides these.....buy a cheep one to try the concept and then get a good one if you like the way it works.
You just can not do that with a scope.