Following.

@ Milroy Paul

I would recommend posting this on GardenWeb on Houzz as that forum would be more appropriate for this discussion. Here are the links:

http://ths.gardenweb.com/forums/homeentertain

http://ths.gardenweb.com/forums/build

http://ths.gardenweb.com/forums/wiring

Ours was hard wired but after putting in replacement windows, was advised to go wireless since drilling into the new windows may void the warranty.

Just make sure to have a battery back up. If someone cuts the wire to break in the system is useless.

If something is not hard wired it will need maintenance in one way or another. Hard wired sensors don't disconnect or need new batteries. Most modern systems are a mix of the two. By the way nobody is screwing on window sensors anymore modern double sided tapes last forever.

Most new systems are camera and motion sensor focused vs the individual window.

I opted for hard wired when we hit remodeled our house in 2012 because I hate seeing the plastic sensors everywhere. When we changed alarm monitoring companies this year they were able to reuse everything but the 'cell' unit.

We are building a new home using a local security company in our town. The motion sensors and window breakage sensors are located on the walls, above eye level. They recommended not putting anything on doors and windows (those contact things that alert you when it separates). It is hard wired and monitored, but we can control it from our iPhones/iPads. They came in and did all the wiring in the wall before the sheetrock went up. We did the same thing with our internet, wifi, and satellite tv.