It's not that dots take more training than do irons. It's that dots take as much training. If a fellow has never fired a gun before, then he probably can learn at least as quickly with a dot as with irons. If he's got decades of experience with irons, though, he's got some work to do to get up to speed with the dot.
As for the cost, iirc the slide cut was $150 with shipping. The sight itself was 450 bucks, which was the best price I could find. 450+150=about the price of a new Glock 29.
As for battery changes and re-zeroing, I hope you are right. I have not yet needed to change the battery, so have no personal experience.