I have an ARP Omni-2 and it has all black buttons. I've searched all over, including here, and can't find anything about it. Every pic I've seen they have the orange and cream colored buttons. Anyone ever heard of an Omni-2 with all black buttons??
Yes, iirc, they're the last production version. They have black push switches, but where they differ
from the Omni-2 version that appeared before them is they have a removable plate(s?) on the underside of the
casing to allow access to the keyboard assembly from underneath.
The units prior to them forced you to remove the keyboard assembly to access the underside mechanics.
The vast majority of the Omni-2's were of the previous version and had the cream/orange push switches.