I personally am all for "flex boards" too, but will you be?
from what i have heard and felt (in a shop) the press is a stiffer "flex board" than most. the lyman is LF's thickest board in the center and it is also the thinnest board in the tip and tails. its thinness actually gives it a fairly noticeable flex in the tips and tails. not a lot, but more than most foam boards.
So between the two choices only. i would go Lyman