Spiff,
i have two flattops..., both Colts, one has a Colt C-More on it, the other has a Trijicon TA31, you mention quality, fortunately for me money is not an object when it comes to what I consider quality..., soooooo, after about 6 weeks of intensive searching i come up wyth three gems, my next optical device will be the Trijicon Tactical.......
now let me explain my choices, Trijicon because they require NO batteries !! i love that donut reticle, 2 MOA inside, 1 MOA thickness of donut, 4 MOA outside of donut, our militarys SEALS, GBs, & other special ops forces use it, they cost about $1,200 but if you look around they can be had for around $800-$900 new, i got mine from a gun auction site, used for $650, i called Trijicon, give'm the S/N & it was made in April 2002, it is fully warranted in my name for the next 15 years on the Tritium lyfetyme on scoce it self, the gas must be recharged after 20 years & todays cost is $35...
the Colt C-More.....!! i got lucky once more, i bought a Colt Gov't Carbine w/ M4 upper & the C-More on it already !!! the C C-More has no "tube" to look thru as do typical scopes, there is a special glass optic held in place by a minimal amount of metal, this one takes a battery, but its battery lyfe is 1,000 hrs. plus !! there is a user replaceable diode that emits light onto the glass, any where you see the red dot, put it on your target & fire away, i was using a "E" O2 tank at 100 yds (thats a different report) as a target out of 50 shots off hand, i hit that sucker 22 tymes, fireing rapid fire, i was getting back on target faster than any sighting device i ever used.....
now, to mounting, you must always keep in mind that optical/glass sights will fail, therefore you must have irons at the ready, both those sighting devices have auxilliary irons..., the TA31, look thru the base & there are the irons.., the Colt C-More has a "tactical" model & it has the iron rear sight as an integral unit...
they are both great, the third sighting device that i do not have yet...! is the Trijicon Tactical, more on it when i get it.....