I'm in the 'no sashing' camp... It's like life: Parts of it overlap and flow into other parts. Sashing is an attempt to control, to keep everything compartmentalized. I hate to see really creative quilts like this ruined by sashing, just because the quilter wasn't comfortable with the freedom in the quilt. It's like putting everything in it's own cage.
I know this sounds a little artsy-fartsy Freudian or something, but it's a gut feeling I have. This quilt pattern is perfectly abstract. Why ruin that?
To me sashing makes really boring quilts. I was sorry to see people take Bonnie Hunter's Grand Illusion and put sashing around the blocks because they didn't understand how those shapes were supposed to play off of each other. It completely stopped the movement it the pattern... but I digress.