Electronic Alarms and Home Security Devices - GE Simon 3 vs XT - X10 - anything else important?

I need to buy an alarm and was looking at the Simon XT but they seems to be fooling with getting the X10 capability working. This is for a small vacation house in Mexico that we are sometimes gone from for weeks or months. I'm concerned about break-ins when we're not there, not worried about intrusions while we're there. So it would be armed and disarmed infrequently. 1400 sf, 2 bed, 2 bath, combined kit/LR, and attached garage with no door into the house. No pets. It is all concrete and rebar. So wireless "strength" might be an issue. Are the XT and the 3 the same in RF strength?

I figure 1 door sensor (main house door) and 3 motion detectors, in the house and 1 motion in the garage, all wireless. I would put the panel in the garage as there are no windows and only one steel door. There is a phone so it could call friends.

I want some X10 light switches so that any alarm turns on lots of inside lights and a siren inside, and outside lights, as there is no monitoring service. Is there a relay or a way to have 12 VDC lights and sirens turned on inside in case the AC power is off? I'd run a fair sized battery and charger.

Question is - is there some capability that the XT has that I need or would want if I knew more - that I wouldn't get with the Simon 3.

I need to buy an alarm and was looking at the Simon XT but they seems to be fooling with getting the X10 capability working. This is for a small vacation house in Mexico that we are sometimes gone from for weeks or months. I'm concerned about break-ins when we're not there, not worried about intrusions while we're there. So it would be armed and disarmed infrequently. 1400 sf, 2 bed, 2 bath, combined kit/LR, and attached garage with no door into the house. No pets. It is all concrete and rebar. So wireless "strength" might be an issue. Are the XT and the 3 the same in RF strength? I figure 1 door sensor (main house door) and 3 motion detectors, in the house and 1 motion in the garage, all wireless. I would put the panel in the garage as there are no windows and only one steel door. There is a phone so it could call friends. I want some X10 light switches so that any alarm turns on lots of inside lights and a siren inside, and outside lights, as there is no monitoring service. Is there a relay or a way to have 12 VDC lights and sirens turned on inside in case the AC power is off? I'd run a fair sized battery and charger. Question is - is there some capability that the XT has that I need or would want if I knew more - that I wouldn't get with the Simon 3. Both systems have the same RF strength....You can use repeaters on both if needed. X-10 on the XT requires the Simon 3 transformer. X-10 will come on for alarms and sirens on both panels. X-10 will not work if AC power is lost... Actually, Simon 3 has a few more bells and whistles, namely dialogue products like a 2 way talking touchpad, RF thermostat, and a wireless dialer (DTIM) that XT does not. In your case however, none of these will probably be something you need....