I had ADT, they did as several others have described, installed a shoddy over priced solution, one that at the end of the day did not adequately protect my home. I was burglarized, the alarm was armed, it did not go off. ADT typically uses 3rd party sales / installers that have no vested interest in the solution they are installing, it's just another sale/install.
Your best bet is to find some a local security company that specializes in DSC, several if you can, and get bids. You can go to the DSC web site and find local distributors. The smaller companies are interested in staying in business by making the customer happy and keeping them happy. I found a local distributor/installer who was willing to sell me parts to upgrade my system to interface the alarm system to my home automation system. (Note that the alarm is interfaced to the automation system but runs stand alone and does not in any way depend on the home automation system to run correctly.) After I was burglarized I went to this company to have them correct the deficiencies left by ADT, mind you, I was still under ADT contract at that point though only for a few months. Once ADT was out, this company took over my monitoring for 1/2 the cost ADT was charging me. Happy ending, personal service by someone who cared, they gave me good feedback like, don't go overboard on the security its a natural reaction after being burglarized, get what you need to protect your house nothing more.