My pref would be a DT (for false alarms, not non alarming reasons) and to contact to the door. If installed correctly they are unobtrusive and if the door is grey etc, then they can be colour matched.
As above a DT won't cure your issue as both technologies have to simultaneously activate to trigger the panel, the PIR element will still struggle in hot environments.
In real terms they are only likely to enter via the doors (regardless of protection) and will go elsewhere.
People rarely go to that much trouble, they will just kick a door in and be back out in <3 minutes.
If you are concerned get a professional in to advise and sort it.
Accreditation bodies want you to pass, it means you earn them money, most I have come across (both SSAIB and Nsi) have been very helpful. Be open and honest with them, they are there to help.
Oh, and good luck.
If anything this probably increases the value on the likes of eBay, they do use a slightly different freq, not locked but only compatible with like for like rx.