Stringing your acoustic to a lower gauge (thinner) string is perfectly fine. Changing to a heavier (thicker) will put more tension on the bridge, so be careful not to put so much tension on the bridge or it may break off or pull away from the guitar.
Comments
If you settle on a thinner gauge, have a tech set your guitar up for it for the long haul. This will eliminate slippage and further tuning problems.
Cheers
Matt