I would give them similar metrics to the ones you give to your marketing folks. If the tech team builds a good, customer-focused product, on time, with few bugs, then the business results will follow. I have seen too much "gaming the system" with milestone or bug-related metrics. If you want to encourage innovation I have found the best practice is, instead of metrics, to give the tech team he space and privilege to do so - e.g., the Google idea to spend 20% of time on whatever they want, quarterly hack days, etc.