I think it's a situation of the proper technique for the proper job. If you are doing straight seams that will meet, pressing to one side to 'lock' the seam when they meet works well. Pressing open or twirling intersections reduces bulk on pinwheels, stars etc.
As far as the long arm quilters, the only thing I've heard is to always press the backing seams open, not necessarily all the piecing seams.
Here's a good tutorial on pressing on this board:
http://www.quiltingboard.com/t-149984-1.htm