I did use one GMerch for a academy, one for philo bulb and one bulb into education (I think) and one into liberalism.
I also generated one GArtist and paired that with one GSci to run a second GA.
So in total 12 Gpersons? GPerson timer is up at 1600 now, so I got that 1400 one at least.
If it's best play is hard to say.
The cost of upgrading is 20+3*hammer_difference, so for a HA (50H) to a Cuir (100H) the cost is 20+3*50=170g. For Cavalry it's 20+3*70 = 230g.
So you are paying 3.4 or 3.3 gold per hammer you want to bring to the battlefield.
So objectivly, it's sort of a very horsehockey ratio.
But it's one of the best ways to convert GPPoints -> hammers, so when you can generate alot of GPeople this upgrading business is one way to turn all those GPeople to something useful.
And it's the GPeople that are broken/overpowered here.
Here, most of those GPeople I generated was done from multiple cities (at least 6 cities contributed) during golden ages while in pacifism being philosophical.
Only the last two (tree?) lagged behind outside the last GA, and the first two GScis where done without either too.
But for the bulk of the points, I was generating GPeoplepoints at 400% of normal. So, say a Gmerchant in the middle of the pack, at 700GPP.
That one costed about 700/ (4*3) = 58 GPeople turns and if we value those at 2 food per turn (starvation can make it even better though) thats 120 food.
The GMerchant then generated 2700G which then converted to 2700/3.3= 818 hammers.
120food to 818 hammers is kind of nice.
But it's also more subtle than that... It's that you can build HAs for a long time in preparation and you can generate the GMerchants a long time.
Then when all things are in sync, you have your techs and you have your HAs and you have your GMerchants then all of a sudden by the stroke of a wand all tech+GPeople+Hammers you have generated materialise on the battlefield.
At T176 when I'm about to DoW, my empire is in kind of a sorry state. If I would just delete all cavalry I would do 250BPT sustained, and all cities except capital are small and suffering from whip anger. The GPeople well is dry (all the low hanging fruits are gone as the next one cost 1600points).
But everything was in sync to summon the greatest power possible to the battlefield.
On this map, where I managed to get 10 cities peacefully, with loads of green land to farm. Population was not an issue at all, and it might have made more sense to do the cuir upgrade sooner, and then just start whipping cuirs straight? But on other maps where you are more starved for land doing this GPeople->Upgrade trick is of even more use than on this map.
But on other maps, you might have bad food potential, and playing a non-phi leader, so how big of a role it plays differs from map to map.
On this map, I would say that the best possible thing you can do, is to get pyramids for rep and take it from there.