When doing an upgrade, gbpvr may update the database schema so you should leave the database as it is. I have never lost any info from my database when upgrading.
Have a look in your gbpvr or oldgbpvr folder for recording-dump.xml. This should (check in notepad) contain the details of all your old recordings and can be imported via config.exe, plugins tab, import recordings.
Silverstone LC17 Case,
ASUS P5Q, Intel E7200, 4GB RAM
Blackgold DVB-T2, ATI 7750, Windows 7 64-bit
SAF codec pack,Sony 40" Z5500