I do both. It's easier for me to match seams with them pressed to one side. But when there are lots of seams, like when two flying geese units meet at the point, or when there's a long seam full of seam intersections, I'll press open.

I do like to "twist and shout." or "spin them" like KamalaQuilts, whenever I can; which starts with nested seams.

Interrupting your regularly schedule thread to say:
That is so pretty. I would be tempted to quilt it inside out :thumbup:.
That is all. Carry on.

About pressing, I don't follow rules, but instead press however it makes the most sense for the block. It just depends on the block.

I am a press to the side gal but on occasion I do get a pattern that suggests open seams and I follow the directions of the pattern. Now, last year my guild was doing exchange blocks and we did find that the blocks measured differently when the seams were open and when they were pressed to the side. The difference was slight, but slight difference over say 6 seams (within the block) makes a difference in the final size of the individual block. We were directed to press seams open to create a more flat final block that would fit together well....and they did. :)

I don't snip and spin my joins. I learned to pop them and they automatically spin. I learned this from Donna Lynn Thomas class. No need to feed them in the machine a certain way like Bonnie Hunter does.

I do both, depending on how the project is going to be quilted. IF it's going to be a bit heavier around the seams, and pressing to one side makes bulk, then I press open. It a matter of preference for the most part. But that said:

My main concern with seams pressed open is will the batting show through after time with open seams. I've had that happen with open seams and often used/washed quilts.