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
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher