I've already done the antenna mode. I built the large antenna with coaxial connection to my CM15a. It definitely helped.
I also extended the wires on a DS10a, but for a different reason. I have one DS10A that's registered to my DS7000. It's connected to my screened in deck door. My theory there is that if an intruder sets off the alarm before even entering my back door, he'll most likely not proceed any further.
The problem I ran into was cold weather kills the batteries. I used phone wire to extend the sensor wire and mounted the main part of the sensor inside. It's working great all the time now.
For the garage door sensor it would be impractical to extend the wires due to the distance to my CM15A. I've heard the RR501 can receive RF and convert to a powerline signal. If so, this would solve my problem.