I've been using my 302 warnings this way since I've owned mine. Works
very well. As stated, it's simple to test the gear up/brakes unlocked
while on the ground. The speed-enabled warning requires simulated
airspeed. I don't really test the latter feature very often. My pre-
flight checklist handles making sure the brakes/spoilers are locked on
take-off. My ship has a very solid over-center lock mechanism. They've
never unlocked on me without me explicitly doing it to apply brakes/
spoilers. My pre-landing checklist also covers the gear deployment
before brake/spoiler usage for landing. I've actually never had the
alarm go off because I missed something or the brakes/spoilers
unlocked on their own. There were a few occasions where I deployed
spoilers to stay out of a cloud at the top of some strong lift. That's
the only time I've heard the alarm in flight. Hopefully it stays that
way. It certainly gives piece of mind to know I won't land gear up.