I normally twirl my centers to, I press to the dark for the first pressing, and then twirl for the second. Because of how this goes together, it didn't really cause any problems with assembly. The problems started with putting the larger sections together. I prefer to nest my seams, so far I've never done a quilt and pressed the seams open.
Kind of funny because I've mostly sewn clothing so pressing seams open was more the norm for me.
Silk - I'm not sure what you are refering to as your "low volumn" colors - is that for the larger background, or the chain? If it's for the background, especially the part inside the circle - I think geometrics would add some really intersting looks, but you may have to be careful about cutting to keep the pattern matching. Like how the "Pink circles" looks in your sketch.
I still am not decided what I want to do, but did put the purples away. I just can't warm up to the way that block looks and this quilt is too big to try to force myself to keep going with that.
I really didn't want to go scrappy, but I've got a lot of smaller yardage so that may be what I need to do. So while I'm trying to decide, I'll finish up putting together a few tops that are almost to the floppy stage.