Yes it is possible to backup the flow logs by removing the --no-logs option from the command line or by selecting the appropriate check box in the GUI. However, there are some things you must be aware of first.
1. You must have enough storage space available for the flow logs as well as everything else usually backed up.
2. You must use the backup/restore process provided in the Profiler and is detailed in the User Guide.
3. The process is very very slow. All the while the backup/resore is being run the profiler will not be collecting any new flow, so you will still see your flow-data-gap.
4. Did I mention that flow log backup/restore is very slow? Well, it's even slower than that! Anticipate a long gap between historical and current data.
5. Backup/restore of the flow logs over a long period is not reliable. Network/communication issues between the profiler and the backup destination will stop the process altogether requiring you to restart from the beginning again. This just adds to that overall slowness.
In my experience backing up the database as normal retains all of your settings and analytics. The analytic baselines are still applied to the incoming flows so there will be no impact on this. But, of course, not backing up and restoring the flow data will mean the loss of any historical reporting.
So, in a nutshell, if you are prepared to risk losing several days of flow log data to retain the existing historical logs then go for it.
BTW, you will need to reach out to Riverbed Support to get new licenses for the VM's you are moving onto new hosts. I think the process is to RMA your existing serial number and new one will be issued. Contact support to get the details of the process.