90% of a cartridges sound is in the cantilever and its tuning (damping, compliance, etc...)
The debate over OCC can simply be resolved by comparing the two styli on the same body (as the bodies/styli are interchangeable).
Even then... vibrational issues are far more likely to make a difference in a cartridge than wire differences... a marginal difference in the body construction would then affect the way that body damps vibration - one body may damp specific vibrations better than the other and vice versa...
This would in turn lead to one body sounding better on specific Arm/Table combinations than the other.
The issues related to cantilever behaviour and vibrational behaviour are "gross" sound issues- with impact measured in increments of multiple db...
Wire purity or grain structure issues are at most measured in tenths of a db.
There may be a difference there, but in now way would it be possible to identify it without first ensuring that all other parameters are identical, otherwise the other differences will completely overwhelm that one (if it in fact exists/is of audible magnitude).
A number of people have over the years mentioned a preference for the way the ATN440ML stylus was tuned over the way the later ATN440MLa is tuned...
You can run an ATN440MLa in an AT150 body (which does have the OCC)...
I have done that and guess what - it sound like an AT440MLa....
When I fit an ATN152LP to the same AT150 body.... it sounds like a AT152/AT155.
Look at the clearaudio MM cartridges - the body is basically a variation on the AT95 (!!).
But CA then go and fit it with their own generator supporting structure - either wood or aluminium, and they have their own custom cantilever/needle fitted and "hard mounted" (non removeable).
So what they have done is taken a very very basic cartridge (AT95), treated it extensively for vibration control, fitted a better cantilever and stylus, and hard mounted it to again minimise vibration influences.
Other people have taken their CA cartridge to places like soundsmith and had them re-cantilevered and re-tipped with further improvements to the sound...
To summarise - the thing that has the BIGGEST impact on the sound (in db impact) is the cantilever, second place goes to the needle (reducing/increasing distortion component in the sound), and then vibrational/mounting issues (which is where headshell tuning comes into it)....
Far far down from that we have wire quality.
(note: I am not talking about contact quality... I am assuming good contact throughout!)
bye for now
David