Tech Pay - flat rate vs hourly/salary

Anyone out there paying good techs by the hour or salary? I have one salary guy. He is a great tech, but not as motivated to produce as I would like. Another hourly guy who works real hard, but thinks he will loose out big time on flat rate, and one flat rate guy who know how to turn hours but is eyeing the "other side" now that things are slow. So far the mix is working. Anyone out there have any really good techs NOT on flate rate?