A common misconception. The USB HID Keyboard Boot Protocol, aka the lowest-common-denominator mode, is very limited and is where this belief comes from. 6KRO + modifiers, limited refresh rate, etc.
This mode is only required for compatibility with certain BIOSes and pre-USB operating systems, though some "gaming" keyboards start in this mode and only switch when they've been twiddled by their driver because a subset of those certain BIOSes won't even boot properly with a keyboard that goes beyond the boot protocol connected.
When booted to a remotely modern OS that has a full featured HID Keyboard driver it can support NKRO, up to 1000Hz refresh rates, etc. and as far as I'm aware is able to match or beat PS/2 in all ways.
In cases where there is no PCB with PS/2, do you know if the adapter when connected to PS/2 has the exact same behavior or are is it a lesser/compatibility mode without the full benefits?
Anytime I sit at a machine where the USB chip happens to reset, I wish it would use PS/2. It's just not the same, and I'm not even using n-key-rollover.
