The ideal stem length for you is a function of your reach. I'm assuming you want to change your current set-up because you feel too "stretched out." Have you had any measurements taken at your LBS to determine reach? I would be hesitant to order another stem before doing that. Also, your LBS can explain the pros and cons of getting a shorter stem. My understanding is that anything shorter than 90 mm can adversely affect handling. I have a 90 mm on my road bike and have been advised against getting an 80 mm for that reason, even though I'm a little stretched out too. I will note that my reach has lengthened as I've gotten stronger. Reach isn't really a static thing.....

Kate