I've never tempered HHB nor Elm, so I am sure your right Marc. My sample size on Maple is small, but my experience in tempering it has been very positive. On par with tempering Hackberry. I've never considered what tempering does to improve the elasticity of a wood, I suspect very little as you stated. It does improve the compression strength, so the belly does less work at a given draw length, reducing set and allowing you to better maintain a given profile. I learned this from Marc St Louis. Sinew will certainly allow you to maintain an even greater amount no question. I'm not making a case here for what is best, just what is possible.