I think the shadows you're talking about are a very personal thing. I've seen 3 A350s on a 210, and didn't really notice any shadowing at all. I don't doubt it's there, but it didn't bug me to the point of even noticing (and i stood there for 15 minutes looking at this tank at the LFS). The single point light source is what a lot of people like about the kessils. I think a little shadowing is a pretty cool effect (i did notice it with the fish when they were lower and closer to the sandbed).
However, this illustrates the need to really see them in person. From what i've noticed, once you get into the high end of the lighting, it really is personal preference.
4 on a 55 gallon seems like extreme overkill to me, haha. Once you're spending $1200-$1600 to light a 55g, i'd start looking at radions.