Hi macom ,
thanks for pointing me to that thread.
In the meanwhile I succesfully upgraded my v4 to v5.5.3-1 with that script and the given commands.
At some point the installer asked me for several modules if I would like to keep my current customized configs or update with the new releases:
Quote from dpkgDisplay More
Configuration file '/etc/monit/monitrc'
==> Modified (by you or by a script) since installation.
==> Package distributor has shipped an updated version.
What would you like to do about it ? Your options are:
Y or I : install the package maintainer's version
N or O : keep your currently-installed version
D : show the differences between the versions
Z : start a shell to examine the situation
The default action is to keep your current version.
I was afraid to maybe overwrite OMV-specific settings when upgrading to the highly current versions.
Nevertheless I always chose to install the maintainer's version - and everything worked well.