I installed an alarm on my IG pool, after an unfortunate incident where someone got into my pool during the night. It is not either of the models that you mentioned, I think the one I had is now discontinued. Mine was permanently mounted, but it attached to the ladder railing, so that it wasn't in anybody's way when using the pool--I just taught the kids to make sure they grabbed the ladder railing rather than the alarm post that was attached to it. I turned it off while we were swimming, and turned it back on when I turned the pool pump off at night. I put it on the pool because I had a large outside dog that couldn't swim, and a sleepwalking older child. It did give me some peace of mind; however, I have two very large bullfrogs that swim in the pool at night and they set it off in the middle of the night at least 2-3 times a week.

We put an alarm system on the house shortly after adding the pool alarm, and that took care of the sleepwalking kid. After the dog died, I quit using it altogether because the frogs made it a real PITA to keep setting it every night and scaring me to death when it went off. So..if the permanent one mounts to the ladder, it won't necessarily be a tripping problem, but if you live in the country like I do, you may very well have a good number of false alarms, which lead to a temptation not to set the alarm anymore.

I agree with Pooldoc, though--your kids need to be taught to swim as soon as humanly possible, and taught where the steps are to get out. Having a pool alarm is a great thing, but the ability to swim is what will keep your kids afloat until you can respond to the alarm. It's very easy to get complacent when you have an alarm on the pool, and that's not a good thing.