Well it will be an interesting experiment and I'm really not being deliberately argumentative, I would certainly like to see spare zones used to split the tampers up to make fault identification easier, it does make sense.Even if it doesn't show a fault if there is a short to a guard zone there is no reason why you couldn't use a zone programmed as tamper to monitor periphial devices like internal sounders or speech diallers.
It only becomes a problem (as far as the standards are concerned) if you use a tamper to protect a detector and both loops are the same polarity.
The standards were written this way because, particualry in a commercial environment, it would be relatively easy for a prospective burglar to short all 4 cores of a cable together during the day time then come back at night and burgle the premises if the short didn't show up as a setting fault.
I must admit I like using end of line wiring, it takes a bit of getting used to but it is so much more secure plus you only need to run a 4 core to a PIR, and you get built in identification of tampers to the specific device.
