I've had Trijicon 3 dot night sights on my Kahr and I've installed a front only Mepro on both of my Glocks. I think that if in a low light situation, having a bright front sight is at least 95% of the battle. Having a rear glowing sight probably isn't going to help the average shooter that has diligantly practiced his or her draw... at least not inside 7 yards or so.
I like the idea of the large dot over a single horizontal bar rear but as I haven't actually shot that config at night, I'm not sure... But it sounds good.
On the Ashleys/XS, I haven't been able to see the big dot night sights in the dark yet... Are they significantly brighter than the standard Ashley or even a new Mepro? In my experience, the Mepros are the brightest I've used.