I'd stay with AUTOLOAD. Just make sure you document it so that people are not confused when they mistype a method name and get informed that the method is not defined in the Connection class even though they called it on an instance of a Device class.

You might also try to test whether the $connection->can($methodName) before calling it and maybe even build and eval"" a delegator if the connection does support that method so that the next call to the same method doesn't have to go through AUTOLOAD again.