I am still trying to figure this out - Jacki you are WAY ahead of me in the gadget department!
My first question is, instead of buying 1/4-round's why don't you buy half-rounds and save the glue-up? Or are you squishing the fabric between the pieces?
And what is the width/diameter of the half-round you are making?
After that I guess I'm just not ready to press like that on a strip - I can't reliably make one WOF straight, never mind sewing a bunch of them before pressing. Mine would be a hilly wavy mess. I always press, measure the width for straightness, then go to the next strip.
But it is true that I can create waves by mis-pressing stuff I already pressed...hmmmm