Chris,
I have no experience with the two remotes you mention, but I have the Harmony 880 and love it. I bought for the exact same reason you mention, to allow the wife and kids to simply operate my system, and my wife would probably kill me if I got rid of it.
As far as I know, the out of sync problem only happens two ways. One, if you turn one of your components on manually by the power switch on the front of the unit, such as hitting the power button on the front of your DVD player to put a disc in. Now the remote does not know the player is on, so when you hit the activity button "watch DVD" on the harmony it cycles the power on you DVD player turning it off. Two, if you hit one of the activity buttons on the remote and don't keep it pointed at the system for a second or two so it has time to send all the various commands.
I basically instructed the family to do everything from the remote and when powering the system up or down the keep the remote pointed at it for a second or two, this solves 99% of the problems. If it does get out of sync it is easy to get back, it has a help button on the remote that will walk you through getting it re-synced, or for me I just glance at the system, see the DVD player isn't on, hit device, DVD, power, and your good to go.