I leave my T1 on all the time. It has a 50K hour battery life. That is over 5.7 years. Given that a new battery costs a whopping dollar one could change it out every year if he or she liked to be abundantly over cautious.
Further if one uses it like a big ghost ring, that will score hits at short distances. I like a red dot but I think it adds much more value on a general fighting shotgun than just a HD gun. A general fighting gun might require longer slug shots where sights really help over a bead. An adjustable sight can also be very nice if one has a gun that patterns a bit off. The sight is easier to use under stress than remembering you hold off.
At HD distances these things are much less of issues. I don't think a quality red dot is really going to be a detriment but I do question how much value is added for the price. I'd rather have it on one of my ARs or AKs.
