Ray can do custom spacings and from what I've seen it is very reasonable.
From what I remember testing in white, a single node is much brighter than a single mini but slightly less bright as a c7 and not even comparable to a c9. I think the 3 led modules go head to head with c9's. I think ss on 6" centers would be very close to c7's on 12" centers side by side and ss on 3" would be comparable to c9's on 12". Note: this is all non-scientific "have a beer and look at some in the basement" testing. Originally, I didn't think this rgb stuff would even compete with the larger incans. It does.