I've used the SMH5 only a few times and already the headset connector has come loose twice while I was riding. I hadn't touched it; I think the wind simply blew it out and I wasn't going all that fast. I looked carefully at the connector and, cripes, there's nothing holding it in place. You need to replace that connector with one with a positive lock. I realize that might require redesigning the main unit as well as the connector, but maybe you can devise something less drastic. Whatever you do, you'd better do it soon or, at least, tell your customers that you're working on it.
SMH5 headset connector to main unit