[Slick]

Assuming no racial construction bonuses, Emergency Build, or population bonuses to construction (which would apply somewhat equally to either situation):

A Mineral Miner III costs 2500/0/0 and produces 1000/0/0, assuming 100%/100%/100%. Assuming a construction rate of 2000/2000/2000, it can be built in 2 turns. Assuming 100%/100%/100%, it will break even after the 3rd turn after it was built for a total of 5 turns to break even.

A Monolith III costs 10000/5000/5000 and produces 900/900/900 assuming 100%/100%/100%. Assuming a construction rate of 2000/2000/2000, it can be built in 5 turns. Assuming 100%/100%/100%, it will break even after the 12th turn after it was built for a total of 17 turns to break even.

Another negative to Monoliths is that in the time it takes to build 2, 5 Mineral Miners can be built, which pushes back the break even point much further when comparing.

A Resource Converter is more helpful to a Monolith, but will benefit the empire no matter what your facility structure is like.

Bottom line: If you need resources NOW, do not use Monoliths. However, if built on planets that have high resource percentages in 2 or 3 of the resources (when you have the time & resources) , in the long run they will outproduce individual resource facilities after a long break even time.

Slick.