We have an arrowhead alarm and are looking at replacing the smoke detectors in the house. It's not practical to have them all wired but AAP do some battery ones. I have no idea what the differences are in using the various different frequencies that they have on offer or the advantage/disadvantage of using one over another. They have a TRX option too which offers two-way communication. Anyone know what we should go for or the advantage/disadvantage of each?