I wouldn't have thought this, but I've just installed this new firmware update, and my OB6 seems to sound even better than before with that vintage knob thingy!
As a bonus, a small issue I had with the LEDs not being all of the same luminosity (with previous OS except 1.2.0) looks now like it's been fixed too!
I've had to install it using the Bootloader though (hold Write+ power on and via MIDI cable), because via USB (my usual way) didn't complete at first.
A big THANK YOU to Sequential for making this update available! You've made a believer out of me.
P.S. that Vintage Knob would also be very cool for the REV2!