I've tried them all and just can't decide.  I'm leaning towards an Aimpoint M3.  What would you get?

(thought the iron sights are excellent for slow fire they have no 'night' option which makes speedy aquisition of sight picture a little hard for me.)

how about u post first a picture of that UMP ?

here ya go.  the ATN ultra sight has found a new home on my CavArms 45.....

That's a nice rig...  Good luck with your search...  Ever thought about the Eotech?

The eotech sits a tad too low in terms of the sights and I find that the reticle is just too damn busy for the close in ranges one would shoot a UMP at.  That's just my opinion though, I know many many people, and heck COUNTRIES, use the EOTECH on subguns.   I put my 552 on my FN TPS, most people would use the large circle to bracket a target in a real fast situation and then hope the bullet goes in the center of that circle.  With a shotgun, I know that at least 6 or 7 of those buckshot pellets are gonna hit inside that circle!  

how about a trijicon reflex ?

the reflex was nice too, sat at perfect height BUT if I ever need my ump it'll be indoors in my apartment form a dark position so as not to outline myself. and as much as I love my meprolight reflex, heck it's on my MRP!,  even i wouldn't want it in dark to light shooting scenarios.  I love it as an outside scope, but not on the UMP.

The aimpoint is coming out ahead here.  I never like the 4moa ones, but this new reticle is shrp as HELL.  magnificent piece.

my only reservation is that I fear I will get it and the aluminum tripower will come out RIGHT afterwards!

That is what I would want primarily if readily available.

I'm thinking of finding some set of iron night sites and just waiting for the new tripower.....

We use Eotech's on our UMP 40's.  They're used in normal patrol and for use on our Swat team.  We also use Eotech's on two of our ar-15's.  Third ar-15 has a c-more(chief's choice, don't ask) that washes out in sunlight.