Nope, wasn't my request. All the 780 series has it.
EDIT: I'm assuming all the 780 series has it. I have never seen the other meters in the series, but it would be crazy if they didn't, as they clearly went to all the effort to include the external header in the original 780 design case.
My personal assumption is, that the BM78x even share the same PCB, since my BM789 contains model markers near the input jacks indicating variants BM783, BM784, BM785, BM786, BM787, BM788, BM789 (with solder dot in mine) and also the "BT" (Bluetooth (LE) variant). Data port for BT is present under the display but unused in the standard BM789.
So it seems unlikely they differ more than absolutely nessasary.
Closeup in my BM789 (see the markings left and right of the jacks):
My BM789 also has the same kind of pinhead as the BM786 (top right):