Hi-- I don't know if I'm the best person for you to talk to as I've only been keeping guineas for a year or so, but I would like to say that I see distinct difference of experience among people who keep guineas for sale or food, and people who keep guineas as pets in small numbers, and then again people (like myself) who have a sizeable flock (now 21) that stays intact as a partner on our farm for insect control (and entertainment!).
The reason I think those 3 different scenarios matter so much with guineas is based on my observation on 2 different on-going guinea threads. What is clear to me is that guineas, being the mostly-undomesticated and therefore close-to-wild animal that they are, have a strong flock structure, and every individual within that flock is dependent on the flock as a whole. Take away any key individual (and there is a hierarchy or "pecking order"), and it affects every individual in profound ways, ways that often cannot be healed. In our flock, 3 guineas in 1 day were killed by a car, and one of the birds turned out to have been a key individual. Their flock has never been as cohesive since, and it's been a couple of months or more. They are happy and functioning, but from that day the flock broke down into sub-flocks that now operate more independently than they used to. I understand there are natural alterations that occur, and as they get older and more comfortable here on the farm their flock dynamics change and have changed, ebb and flow. But because of the extreme difference of behavior before and after the day she was killed, I know it in my bones.
So, just saying, someone who removes individuals from the flock for food or for sale is not going to see the kind of flock cohesiveness, and the flock-intelligence the individuals depend on, that an intact flock has. And someone with just a couple of birds (I've heard 10 cited as the number that begins to act like a self-contained flock) doesn't see the flock part of these birds either. All must be and are valid experiences, but they are very different.
That's just what came up for me in response to your request.