On the majority shareholder bonus: indeed, it is not for depositing the majority of the minerals. Thanks for providing additional evidence for that claim, Taco.

As for rewards: the biggest variable affecting rewards seems to be the age of the gate. If I invest in all gates equally, my rewards from all of them seem to decline as the gates age- even when there are more players, and when no new gates have opened. So although we have now re-hashed the stock explanations, the entire point of this thread is that I am not sure that the "conventional" explanations are complete, or correct.

On a different note: the new gate experiments have shown that even for a core gate that was more than 50% red minerals on the totem, the resulting proportion of actual red levels was much smaller. This would seem to suggest that:
a) Very pure deposits are required (favoring large all-at-once dumps), and
b) Dusk drops are basically mandatory for getting anything other than a melange of clockwork tunnels
c) The blue/purple gate produced haunted, devilite, and mechanized mile levels, which are also associated with depositing only one mineral type. It appears that mixing [those] two colors does not produce new unique levels of a third type.

If these statements are true, it sounds like dusk drops are required if you want to build interesting levels (since "pure" mineral deposits need to be separated from the general milieu)... but fun levels seem to pay out roughly the same as boring levels. What reward incentives are there to balance the added costs of making "fun" levels? (Fun is enough for me- but I'm not the one with all the minerals)