I see from the latest issue of Descent that the depth for OFD has gone over the 300m mark again, with new finds in OFD 3.
The vertical range is now 312.5m.
The long quoted depth was 308m but that was reduced to 291m after a resurvey published in 2014. Now, climbing in OFD 3 has added height to the system, it seems.
All info taken from Descent.