As it is now the only siren your alarm system has is on the panel. In our house the panel is upstairs and the siren can barely be heard in parts of our basement or not at all in the shop. If our alarm goes off you can't even hear it outside; wouldn't it make more sense to have a siren outside so neighbors etc can hear when it goes off?
It would be nice if you offered extra internal sirens that could be plugged into any outlet but it would really be helpful if you offered an external siren we could plug into our soffit plugs.