I dunno! I don't think anyone really has a handle yet on LED growing (including me). It is going to take a while to get thinks optimized. At this point we are all just screwing around, having fun.

I think a very flat growing surface is what is going to work with LEDs tThe penetration ,even on the best of them, suck. The reason I am placing lamps very close to the plants is because K2s have a very wide viewing angle of 160%.
Working with different viewing angles will play into your design. If I was using Crees with a 90 degree angle, I would probably have the lamps a couple of inches higher. Or if I was using a 30 degree lenses, the design parameters change again.
The array I am building now, will have 2 different types of lamps in each half so I can do some comparisons of different light angle and drive current.

Yup, I tend to agree with you regarding light on a single plant, no free lunch.
My designs are going to be more geared towards a green carpet as opposed to discrete plants like in the SNSealth initial grow.