If you ask me, any dude who puts a reflex-type sight on a Shotgun is one of those rare individuals who is able think outside of the paradigms laid down by the gun rags that all you stupid hogs read.
Dot/Collimater/Reflex Sights can not be more perfectly applied then on a shottie.
The nature of the shotgun, and the nature of the dot sight go hand in hand like ghettos and the smell of cookin fatback.
Fast target aquisition afforded by the dot sight is usually at the expense of paralax, even on the more expensive sights (The ACOG and Gilmore being glaring exceptions)-
This paralax is very detrimental to long range accuracy, but on tools like shotties and pistols which are meant for inside 50, they are a godsend.
Good job man for thinking for yourself, and using common sense to apply accessories to your guns, rather then just "what the gun mags say".
Nice rig, and I hope to build up one similar myself one day.
McUZI