updating to latest osm2pgsql

Hi all, we are using two different versions of osm2pgsql on two different servers to import and keep up-to-date OSM Europe extracts.

We'd like to upgrade our osm2pgsql binaries to benefit from some of the latest improvements.

On one server we are using osm2pgsql 9.6.0 with -G and a flat-nodes file. Can we safely update this binary to the latest osm2pgsql (1.0.0) and keep our existing database and flat-nodes file ? I see there have been changes to the handling of multipolygon, but I don't understand whether they are breaking compatibility or not.

On the other server, we are using osm 9.3.0 (dev) without -G and with a flat-nodes file, could this be updated as well ? I the changelog I see there have been some breaking changes to the slim tables. Do I need to reimport everything then ? Or can I for example simply update the osm2pgsql binary and then use the flat-nodes file from the other server ?

Thanks a lot for your help on this !