I've found the tritium quite useless. The only time I've ever seen it light up the reticle is when I've gone into a completely dark room, but in that case the very dim reticle is the only thing you can see through the scope. With the fiber optic models that I have, if there's any light outside (just before dark) the tritium illumination is still overpowered by the light gathered by the fiber optic. Again I suppose I could tape over the fiber optic so the tritium has a chance to shine, but the fiber optic is better than the tritium in the just before dark scenario.
On the ACOGs without the fiber optic like you have, I could see the tritium being more useful since the fiber optic isn't there to overpower it in the lighting conditions where it might be useful.
But, like most people I don't shoot much in diminishing lighting conditions, so the tritium might only come into play in some weird situation I can't really anticipate. Though by then the tritium in my ACOGs will probably have lost it's charge anyways. Heck, my first ACOG's tritium is probably already un-seeable at this point... It's just not something that I keep tabs on.