That yale system is a low cost, easy to install DIY package, you can have it working in half a day and the batteries will only need changing every year or two.
You say you're after an alarm for piece of mind with your family at night, and it will do that. You can set the front and back door sensors so they chime "bing-bong" every time they are opened, which is useful if an opportunist thief tries the door handle when it is not locked, also if you have small children who might get out into the road.
You can buy an additional siren cheaply on ebay, and fit it, say, on the landing ceiling where it will wake the family, and the loud noise is said to stress an intruder.
If you have a telephone point in your bedroom, you can put the control panel there, so it is well away from interference at a likely entry point, and can dial out before anyone attacks it. It will phone three numbers of your choice. Once the siren has started, disabling the control panel will not stop it. The panel has an internal siren, and you can set, unset and interrogate the system from the panel. In the event of an alarm it will show you which detector(s) were tripped. You can add sensors to your shed or garage if you want. Unless you live under a radio transmitter mast, or your neighbour is an arc welder, you are unlikely to have interference that prevents the signal getting through during a break-in. If you want, you can add wireless smoke detectors to the system, and you can add a large number of additional door or movement dertectors if you have a larger home.
If, as I suggest, the panel is away from the door, you can have an extra keypad concealed near the door which people can use to unset the alarm with a PIN, or set it with a single button when leaving the house or locking up for the night.
If you do decide to get the extras, the cheapest way to do it is usually to buy the basic Yale "Standard" alarm kit (with no control panel) which cobtains a siren, a keypad, and four sensors. Ther parts are fully compatible, you just have to change a setting in the other siren. the sensors from the previous model of Yale alarm are also compatible and very cheap on Ebay. this alarm is nt compatible with the new Easyfit range which is said to be better. Check prices at Ironmongery Direct and DIY sheds as they vary.
I have installed three of these, and find it an advantage to set it up and test it on the kitchen table, before screwing al the parts to the wall. Wrap up the siren in cushions for test as it is very loud.
With more money and/or effort, you can get a better alarm. Some people on this forum do not see the benefits of a low cost, easy to install DIY package, but i do.
