...I was thinking more of a burglar who would be targeting specifically x10 homes....
I've never in 20-30 years ever had a neighbor that used X10 even when I lived in apartments. That means the number of homes using X10 is still a small percent. Way too small a percent for someone to specialize in targeting them. That said, my garage remote has thousands of possible codes that change on a roiling code system. I wouldn't want to trade that security for a handful of possible fixed X10 codes I could use. Furthermore the range of most X10 remotes is poor, particularly when trying to send a signal through a metal garage door. I can use my garage remote as soon as my house comes in sight. With an X10 remote, I expect I'd have to be in my driveway and wait for the door to open.
If you do choose to open you garage under X10 control, I'd recommend increasing your security a bit by plugging a universal module into another X10 module so 2 codes would need to be used to open the door.
Now I
do use X10 to close my garage. Basically I have a reed switch wired in series with contact of a universal module. The reed switch is only closed when the garage is open. This means an X10 signal to the Universal Module can never open the door will always result in the closing of an open door. My door closes automatically when coming or going as well as from my shutdown macro and my power restore macro.