Report any bugs you think you may have found because you are working with the latest and greatest drivers! If your bug is backport compatibility-related then we should still try to fix it within the compatibility layer. If you are not sure you can let us help you. To date we have only have identified 2 backport related bugs, all other reported bugs were real bugs in actual upstream code!
We are working on a bugzilla entry for compat / compat-drivers, until then please report all bugs you think you my have found to the backports mailing list and if you know what subsystem you think the bug belongs to Cc: the respective mailing list. Remember that chances are high that the bug is not a backport bug but instead a real upstream bug that must be fixed.
For future reference: backports bugzilla