rs1800

I have a couple of questions if anyone can assist please before I order. I am using 3 x tritechs in house (a little ott but for pet tolerance) - I also have a conservatory that gets very hot but will not have pets. Should I just use another tritech or would a DT7450 be better? Has anyone used the Texecom Odyssey 5 compact or is it best to stick with full size? I have 3 x M12 smoke alarms on 1 zone and my installer doesnt have much experience of fitting these when using resistors. He was going to check but can anyone advise what may be required else we will just wire the whole system with seperate tamper circuit. thanks