That's correct...if left connected to a signal, the box eventually updates...could take weeks tho!!
I always believed the presence of 11778V is necessary for the box to update software...
Recently i had problem updating an Amstrad DRX890 which had EPG software version 45.X.XX.X..
No matter how many times i tried to force an update, it did not...this box had the EPG in the old order (ie SKY News on #501 instead of #517)
I left it connected to my dish and it took almost three weeks to update to EPG software version 47.0.16.1...but
EPG s still in the old order!!