Roger,
I ran an SBS-1 for a year before I got my Radarbox, so I did import the BaseStation SQL file and RB successfully grabbed the majority of the records. It ignored a few that were corrupted, but I was more than happy with the results. Note that the imported aircraft details will go into your MyLog.db3 database - the historical record of aircraft you have picked up 'live'. The SQL inport will not populate the source RB database NavData.db3.
In short, it is the NavData.db3 file that is quizzed to provide the data to fill the aircraft lists and MyLog records.
As the Autopopulate function populates the NavData.db3 file, inporting a SQL file to MyLog will not stop the autopopulate function working in RB.
If you are trying to populate the source database - NavData.db3 - by importing the SQL file, this won't work. It doesn't really need to either, as this will get populated as RB runs.
I hope this helps.