Nismo,
Hard to tell about possible inconsistencies between different batches of tritium tubes, but I can add a couple of things which could either help clear or muddy up the water further!
The last time I qualified I stood behind a line of Officers who were shooting our dim light qualification course. I was at least thirty or more feet behind them and behind glass, but I could clearly see all of their sights from where I was watching. All of the weapons were the same, but with many different issue dates on those guns. All the sights were Trijicon.
Before any piece of equipment hits the streets it is extensively tested by our Range. Our Range staff is made up of Patrol Officers who use the same equipment we do. Opinions on equipment are taken from many different sources, but in the end, our Department tests everything we use in house. We've got about two thousand Officers to outfit, so if something doesn't work, believe me, the Range will hear about it post haste from the rank and file.
And although cost is taken into consideration for any piece of gear, my Department actually issues very good personal equipment. Some of the best. Last time around they bought Trijicon sights over the less expensive Meprolights. Could be something there.
We're transitioning to a new weapon this year so I don't know which sights they'll pick for that one, but they did choose the most expensive sidearm out there--with all the bells and whistles. A shocker for us. It was the only one that took everything we could throw at it and still fit a very large and diverse group of personnel. And we tested all the top autos. I don't know which sights they chose for the new weapon, but if I was a bettin man....................
p.s. I'll find out which ones next week and add to...................
p.p.s. I also wish they would start buying the Crown Vic's again!!