I run a replica EoTech on my m4 and I have to say it makes life 10x easier than using an iron sight. Just put the dot on the bad guy and pull the trigger.
(I only play CQB btw)

It also should be noted that tritium vials generally aren't very bright. I affix them to my keys and flashlight to find them in pitch dark. In the situations of low light, they're dim at best (especially going beyond simply green color).

Well thats kinda why people use them, a faint glow when looking through a sight, allows you to use the sight and not give yourself away all too much

I'll have to check it out. I guess when you're in constant darkness it would help. If it's dim, then your eyes may have trouble picking it up quickly.

Hmm... That's not what I remember the tritium's for... It's not so much as the glow allowing to see the iron sights themselves, but having 3 faint glowing dots that let you line up a target. Think of pistol tritium sights. Even if it's dim, it'll glow a different colour than the background so you can see it.

My ice blue vials glow quite nicely and really bright, so I don't know if your vials are getting old or just the manufacturer?