Well, the poll is now closed and it came out 17 to 4 in favour of dbm.sqlite3 being the new default. Interesting! 21 votes is a decent turnout, but not an overwhelming one; dbm is perhaps not the hottest topic 
(My PR does not make dbm.sqlite3 the new default; there is plenty of time to make it so before the feature freeze, if we want it that way.)