Any experience with Night Master 400 IR?  How does it compare to T20 IR?

Yes to your first question, no to the other ( still waoting for it to arrive, to see what the fuss is about :) )

Check out the will a ir help a gen1 thread ( think on page two ) might give you a idea.

Is it just me, or does the name "Night Master" sound retarded?

I'd much prefer something like "The Black Death" or "Nuke Dukem: IR SOPtard."

Thanks.  The ARMASIGHT IR used in your comparison is a low power version IR (120mw)?  The high power version "W" (IR850W, etc) is 500mW.

It seems the brightness of nm400 is about the same.as nm800.  That makes sense since they both use the same power IR LED. Of course, the nm800 got a huge lens and should throw farther.  What's the beam angle adjustment for nm400?  Armasight IR850W can adjust from 2 - 30 deg.  Is nm400 spot beam smaller or bigger than Armasight?

Well, night hunters are retarded people.  That why they hunt at night! ;) So the name conforms to their users, IMO.