Hypothetically speaking, what would happen if Portuguese could trade food for gold at a 1:1 rate?

Before I start: please bother to read all points, as I'm not saying it would be 1:1 for certain, and moreso just pondering about various market bonuses we could still explore.

Since the release of the new civs, I've been thinking that civs like Poles really drive home how underperforming civs like Portuguese are: they enjoy practically no early bonuses (research time needs several ages to matter at all, gold is always an inferior bonus to food/wood) and excel moreso in the late game, but civs like Poles do far superior in all ages leading up to an equally solid lategame. Same can be said for civs like Magyars, who while they have no direct eco bonus early, have a good early rush and a phenomenal lategame.

So I started thinking what kind of balance changes could be made to balance Portuguese out since they've consistently ranked bottom.

My first thought was what if we took the Saracen market bonus and gave the Portuguese a stronger version, but limited to one resource only, namely, food. Then I realized the Saracen bonus already reduces initial prices to 5% difference, so it's difficult to beat this unless....well, unless you get a 1:1 trading price.

And this got me thinking:

1) How would such a bonus actually play out? The exact bonus changes with each transaction, but I'm unclear on the equation and how it changes each time. So if Portuguese traded 100 gold for 100 food, what does the next transaction look like? 101-99?

The wiki claims each trade reduces/increases value by 2, so this would mean it drops to 98, then 96, etc, and would ultimately not be that much better than the Saracen bonus. Perhaps an additional tweak to the rate of price decay? Portuguese buying/selling only increases/decreases price by 1 or .5? (aka every second trade makes a change)

2) How strong would this be? An argument can be made that gold is easier to mine than food is to collect since food has the most complex method of collection. You can't simply start a farm, but rather you need wood for it, meaning you essentially need two workers for one job. (one lumberjack and one farmer; the ratio isn't exactly like this of course, but the point being in Feudal you need to get lumberjacks first, farms second)

This bonus would enable Portuguese to fully focus on gold and simply trade for food, meaning their archer rush could be especially potent or their fast castle could be done with less vils, though it's difficult to say if it'd be worth fast castling with fewer vils. Theoretically, yes, because again they can simply buy the food to produce more vils.

On the flip side, a Portuguese civ dependent on the market to buy food would very quickly drive up the buy prices for food, meaning other civs can potentially exploit this for their gold reserves.

3) Is it OP? I mean, Saracens are already just 5% away and no one complains about them being broken. Portuguese saving 5 extra gold/food on that trade hardly seems broken when you compare whilst still giving them a more potent early game. The main draw would be that their food market would be less susceptible to price decay, giving them more long-term value on the market trade that can be exploited for longer.

This is less a discussion about this particular setup (food/Portuguese) and moreso about what you guys think of such market-based bonuses in general.

I feel like there's real potential for some good future eco bonuses with the market, but it's difficult to say how strong/weak such bonuses would be. I mean what if we had a civ that always traded at 1:1 with food? That's obviously a huuuuuuuuuge boost to their lategame to the point they'd be the best lategame civ period, but I think the more interesting question is how such a bonus would effect Feudal/Castle. I can't quite decide how strong it is for Feudal, but it admittedly sounds disgusting for Castle, allowing you to simply buy the food needed to sustain your boom and still produce military without delay. It does seem like the civ would - of course - be ridiculously vulnerable to tower rushes or attacks on their gold though, as this would singlehandedly shut down the eco bonus and leave them scrambling to find more gold or to repair an otherwise awful economy by redirecting everyone to food/wood.

Thoughts?