We've built several ERC longbows in the past ... 72" ELB style , backed with thin hickory and bamboo ... 60# @ 28" ... Wood was harvested from a friend's hunting lease in Mississippi ... Backings were about 3/32" .. Never had any problems , all were sweet shooters ... Light in the hand , somewhat thicker D cross section ... and I was able to shoot larger /heavier arrows (ramin wood dowels ) with adequate speed and good knock down power and very accurate ... 50/50 sap to heartwood , even some small knots ... Easy to work , smells great ...
I even did one backed with polyester camo cloth (2 layers) ... "not Primitive" , but an Easy alternative backing ... shot just fine ...
Ps. I did glue on the backings with some "Perry reflex" , so all had very little or No string follow after shooting ...and would creep back into some reflex as the bow relaxed...
Never tried an ERC board bow , but that's next on the list ...