Anyone have any great knowledge of these god forsaken things?

It seems like every other job I get a "bad" one. We wire our smokes on their own 15 AMP circuit and interconnect them using 14/3 romex. They go on an arc fault breaker. We then use a combo unit in the basement if there are gas mechanicals. Anyone see any problem with that. The combo units are the same manufacturer as the smokes. Typically what we are getting is that when you push the test button at the combo its sets off all the units except itself. Its driving me batty!

Are these things simply that unreliable or are we doing something wrong?

Any thoughts?