I've got a Siemens Gigaset dect phone. The battery life is about a week (runs on 2 heavy duty AA batteries) after about 5 years still. I've never had any problems with it, and while I haven't ever tried it out over a distance of 200m, I do know I have perfect reception when I'm in the back of the garden. Even in our old house, which was heavily insulated, we had perfect reception outside. They do claim a 300m range outside. The set we have can have 6 units connected.
When we bought our first set, we found out a lot of stores use it as well (everywhere we came and a phone rang, we recognized the ringtone

)