Some number working...
Planks are my boost, so I evaluated from there using basic unboosted daily production rates
Production / Square : L15=29 L19=37
Population / Square: L15=65 L19=116
Production / Population: L15=.44 L19=.32
The good news from this is that score can be increased effectively, since we can load more working population into the spaces (if we can get the population to add...) I've read some beta comments where players consider the efficiency of population (as in this case, where the working population becomes less efficient)...but to me it's most important to 1) get the production I need to progress and 2) maximize scores. Anything that increases the working population / grid square seems beneficial.
Let's say I have 30 grid spaces devoted to planks and don't want to use any more space. The replacement ratio is 3:5, so I upgrade 3 manufactories and delete the other two - still using 30 grid spaces. The exchange produces break even production right away when they upgrade to L16. From there the benefit increases. Three L19 planks produce 29% more than five L15's for the same amount of space. Same space, more production, higher score.
If I want some extra grid space, it works to delete some manufactoires. A L19 produces 115% of a L15. So, beginning with two L15's, I update one to L19 and then I can eliminate the other L15 and have 6 available grid squares and 15% more production. Extra space, slightly more production, higher score (all based on whether I can find the apx 400 extra population).
As an intermediate strategy, it may be interesting to upgrade as many of the planks as possible without deleting any for now. Basic goods are currently in shorter supply, so they can be traded to advantage personally and for the fellowship.
Most difficult to implement is the new ratio between residences and manufactories. Previously we needed .8 residences for each L15 plank. Now the ratio is 1.6 :L16 and 2.5:L19.