Yep, I leave well-enough alone, however if a BD doesn't play or you have issues, the first thing you should try on your equipment is a firmware update. Firmware that was developed in 2009 for a BD player may not play certain features on 2010 BDs or certain 2010 BDs, for example.
One additional update option is via USB stick, as you noted. Update procedures are usually covered in the operating manual.