After re-reading my previous post I recognize my answer was not clear, saying "without putting in basic work". In my mind a guest can work (without any production value) but can also be a manager, giving it more value than a slave which can not manage.
But in any case I can't agree to the fact that a guest would produce more than a slave. On the contrary as a slave have generally a lower maintenance cost (less food, less confert, ...) with the same production (with same physical stats), the production ratio is better.
It is the eternal debate love/fear due to the fact that ppl can't imagine what really happens in some hidden part of our "civilized" cultures. Go and ask the prostitutes in the streets to see if they accept that per love/pleasure or per fear/needs...
You're looking at it primarily from an in-game perspective. I'm looking at it primarily as game mechanics. We're not going to come to an agreement, because I don't care what the actual in-game justification of the mechanics are, just that the game mechanics are balanced. I don't care why, for example, we only need to eat once every 3 days, or why there's no hunger penalty from not eating every day. What I do care about is that food production is balanced around that 3 day eating schedule, and if, for example, we suddenly have to eat every day, then food production must be re-balanced around that. If we did have to eat every day, there's no in-game justification for why food production should suddenly triple, but I would argue that it should to balance against the tripled consumption.
Ultimately, guests can't be a manager and a worker because, in my proposal, I'm saying those are 2 separate jobs. And they're 2 separate jobs because not doing so makes a full guest build be not viable compared to a full slave or a mixed build. But if you'd like to share the formula you think that a guest should have on boosting slave production, then we can discuss that.
For the record, my formula is:
Slave: 2 food/3 days
Guest: 3 food/3 days
Overseer: Boosts up to 4 slaves per overseer, no food produced
Slave (boosted): 3 food/3 days