Good news. Here's what our contact at BenQ said:
It's true that BenQ is working for the 4x DL writing firmware for DW1620. After firmware upgraded, the specification of it (DW1620) is the same as DW1620 Pro which is going to launch next month.
Apart from the 4x DL and bundle software (Nero Suite), the retail packing is the only difference between DW1600 and DW1620 Pro. The production for DW1620 will be stopped once DW1620 Pro is ready.
Consider to the DW1620 users, there is a FREE firmware for such upgrade
which likes the FREE firmware for DW1600 upgrade to DW1620. In a word, both DW1600 and DW1620 users can enjoy the new specification (4x DL) of DW1620 Pro via an easy FREE firmware upgrade.
Stopping prodiction of the 1620 already? what is going on here...I thought it just came out? This is a bizarre industry