There is a specific fuel imbalance procedure that is run in case any fuel balancing is needed. Just opening all pumps and hope for the best might lead to some rude awakening. It has happened in the past and probably will again if used like that, and of course stuff like the OP experienced is a direct result of that.
And yes, opening the xfeed outside the scope of a procedure is very actively discouraged. By the way, both on the bus and the boeing in my outfit, for the same reasons. Just the limits are much tighter on the boeing with 453kgs imbalance instead of 1500kg on the bus.
As NoD said current software on the bus only uses the line "Monitor imbalance" which does not mean to push the xfeed button (although that still removes that line), instead our FCOM advises us to actively monitor the fuel situation for both leakage and imbalance. Writing fuel quantities down and comparing them later to fuel burn is a very good method of doing that. After all we have that nice table for our pen and paper...