What determines the efficiency of electron production in photosynthetic bacteria?
You may or may not consider this an actual answer to your entire question, but it's interesting nonetheless.

A physicist friend of mine did some work recently modelling the quantum dynamics of photosynthetic complexes, and their coupling constants for passing energy throughout the photosystem. His results showed that, (and I believe this is in agreement with the literature), that photosynthetic systems are actually about as efficient as it is possible to be (not only this, but they are the most efficient energetic systems known to man I believe - over something like ~90% efficient).

If you begin altering positions of chromophores and so on, the photosystems exhibit remarkable robustness and you get a more or less logistic decay in efficiency (i.e. removing one or 2 chromophores results in marginal reductions in efficiency, more still in considerably more severe debilitation, until ultimately it's efficiency is markedly lessened, but further manipulation has a plateau in efficacy reduction).

Much of the work that's been done on the quantum biology of photosystems has concerned the FMO Complex (Fenna-Matthews-Olson) which is a simplified model system from photosynthetic algae - you might find more detailed answers to your queries by reading up in this area.

As for discrepancies seen in photosynthetic effectiveness bought about genetically, there are theories that suggest that the organisms are actually protecting themselves. E.g. to avoid over-production of ROS species. I can't offer you much in the way of a well evidenced case for this though, it's just a conversation I had with a post-doc at work recently, who completed his PhD on photosynthetic cyanobacteria.

EDIT Here's one of the papers about optimality in the FMO:

http://aip.scitation.org/doi/pdf/10.1063/1.4930110