While I only have them (tritium) on handguns myself, they are quite easy to see at arm's length. Can't see why a rifle or carbine would be any different.
Personally, I think that there are many practical advantages to them over any battery operated 'red dot' or holographic sight out there.
As they supply their own power, they won't ever be rendered hors d'combat for want of a battery.
They are much more tolerant of rough handling or hard use. Even if one of those little vials should break, you still have a usable set of irons. If your battery goes out, or a component fails, a red dot is essentially useless.
A set of tritium replacements has no affect on the handling characteristics of your weapon. Most electronic sights that I've seen impede carry at the weapon's balance point, at the very least, as do most telescopic sights when mounted in the conventional manner.
While there are some 'tactical' types who worry about the possibility that emmanations from tritium or electronic sights will 'give away their position', it's my personal opinion that a red dot is more likely to do so than tritium, as it's visible from more angles on both sides of the muzzle than are tritiums. On my CCWs, I don't give it much thought as I don't go looking for trouble and, if it should find me, we'll both already know where I am.
FWIW, the sights on one of my primary CCWs, a Para C7.45, are XS Big Dot tritiums. IMO, they're about the fastest to acquire a good usable sight picture with of what's out there at this time.