Hi Nick, I am slowly switching everything (even my air pump) over to 123s. I dont have that much time on them yet but am very happy with them so far. They are listed as 2300Ma but I am getting about 2000 out of them. For me they scratch my itch for the following reasons:
1-retain 95% of charge for a month (unlike NiMh or Nicd) This works well for me as I dont get to fly very often. With Nimh if you let them set you get false peaks if you fast charge them.
2-true 1000 cycle life times. Lipos state 2-300 but I have never even come close to that before capacity drops
3-No need for a regulator- nuff said
4-Dont blow up if over charged. You can kill them by ovrecharging but they wont blow. (ask me how I know)
5-Tuff to kill them by overdischarging
6-You can charge them at 10 honest to god amps. You can top off after a flight in the time it takes to fuel
yes or nos-
1-They are light but bulky so not so great for tight quarters (never usually an issue)
2-Need a special charger.
3-They are getting REAL DAMM expensive

You will love them, Scotty