Dots are fun....BUUUUUUT...it depends on the person, the reason for the dot, and how much they are willing to PRACTICE. It all comes down to LOTS and LOTS of PRACTICE.
I built a .40 Open top for my G35, with a dot (pic below). Runs great...and I like the Dot...very quick to pick up and it's accurate....HOWEVER...it took ALOT of practice with it to get comfortable with it (especially running at speed on steel).
I don't run one now...1) My eyes are still pretty good (at almost 52)...2) My duty gun has night sights, so I run the same on all my guns for consistency....3) I've found that I'm just as fast with my fiber optic sight on my competition STI and night sights as with the dot....4) Running a dot had me indexing the gun differently, which messed me up a bit with my duty gun.
Dot's have a place. I've seen guys run them in USPSA, but without alot of practice they are just waving the gun around looking for the dot! LOL.....with iron sights I feel you can get them re-aligned quicker. You need to really practice with it because: 1) The gun indexes a bit differently, especially with a slide mounted optic that isn't melted in....and 2) The dot will jump and you'll have to find it in the window again.....
I agree with others....battery life not an issue...I run red dots on my M4's at work and those things last a long time with regular batteries...LOL. I just stand by what I said above....indexing the gun is different....finding the dot is different.
When my eyes really start going....I plan on the Dot route...LOL
I'm going to give some examples and they may or may not help or even make sense to you,...but here goes.
Changing guns (and grips) is very detrimental to using a Red Dot. Here's how I got to really appreciate Red Dot Sights.
First I believe you NEED to have back up irons (at least in the beginning) that co-witness to your Red Dot.
You need to find your Natural Point of Aim that allows the irons to line up naturally, then adjust your grip accordingly. Without a grip that allow a NPA upon every presentation you will always be "looking for the Dot".........In other words you grip and presentation needs to be the same every time. This will allow a "Natural" alignment of you irons and will put the Dot in the glass every time.
If you can maintain that grip and presentation then the irons seem to disappear and you won't really see/need them any longer.
The above is why I believe changing guns (at least ones with different grips) is why most folks have problems adjusting to Red Dots. Same gun....Same grip...NPA...instant Red Dot. JMHO.