I would keep your HJ seats. If the flight looks incredibly empty hours before departure, such as where you see nearly all the CDEFG seats are unoccupied, then I would go ahead and re-assign to those. It's a gamble still, but the odds are in your favor. But, if you are seeing that the seats are mostly occupied I would keep your HJ seats. E seats could always go out to someone on standby or to a non-rev. Happened to me recently on a B6 flight from LAS to JFK. Bought a $45 EML seat and up to a few hours prior to boarding there were at least 30-40 empty seats in the back rows. I regretted the decision up to the point when I heard an FA complaining that 32 standbys/non-revs got cleared. Just goes to show that even when you think a flight is empty it can go out nearly full.