ERC and sinew are like peas and carrots.. I built a fine reflexed sinew back erc flipped tips.and she screams at 51@26.5.. extremely lightweight in hand.. love that bow.. you have to till slowly with cedar ..once floor tilled and braced I tilled with sandpaper ..very soft wood.. easily dented.. compression is fabulous however tension isnt as strong hence why backing is required for a heavier poundage bow....also erc is not commonly free of knots so a clean piece is a great find..I agree all sapwood makes a fine bow..mine only has a tad of heartwood on handle...gut