I recently did a 56in, bend thru the handle, backed with rawhide. When it was finished it was just a little too heavy to pull with my shoulder the way it is, last night I shaved about 10lbs off it, it's alot easier to shoot now. I found something with my bow when working with the ERC, maybe it's just me but I tried heat bending this stuff numerous times to remove some deflex, it just didn't come out. Maybe it responds better to steam?. The finished bow is super light in the hand.
Good luck with your project. There are people out there who have worked alot with ERC.
As far as your question about which pc would make it, it's hard to say but I think you'd have less problems with the shorter one.
VB