Unless you are looking for the features that have been released port 9.2, I would recommend staying with a release that works. Feature changes are made in the major releases (9.1, 9.2 etc), so there are more chances of hitting bugs that could affected existing services. Going to an interim release within a minor version (eg. 9.1.6.8 to 9.1.6.11) has a lower chance of hitting new bugs as mostly bug fixes are put in those.
Having said that, Cisco could EOL an older release which would force you to move to a newer one to keep having support, for eg.9.0 and 9.3. So you might have to upgrade to the newer releases to keep up with Cisco.
