Can OMW 8.16 be upgraded and migrated over to OML 9.10 ?
I believe you can migrate policies from OMW 8.x to OML 9.x server. However when it comes to SPI policies - note that SPI version meant for OM-Windows server are not the same as SPI versions meant for OM-L (or even other OM-Unix) server.
The SPI policies (and the instrumentation) themselves will not be an issue for I am assuming that you are also going to migrate the nodes that have these policies and currently managed by OMW 8.1x server moved over to the OML server. However if there is a patch/hotfix or even a new SPI version then things may break.
Hope this helps.