Since any osage I find around my house tends to be dropped off by the post man or UPS, I don't tend to pass on much of it. I take it as it comes.
That little trick of backing with rawhide is great ammunition to keep in your war chest. Yeah, high early growth to late growth isn't optimal. But has anyone actually done a good scientific comparison head to head? Are we talking 10% slower? In an average 150 fps from a 50 lb bow, you still have more than enough energy to do a thru-and-thru on a deer.
So if you end up with an RPI that you like, and the early to late ratio isn't amazing, push yourself to milking the very best from the bow with better design and execution. It's all about the challenge of doing your best with the materials at hand. If your final criteria is performance, go play with space age polymers, wheels, levers, hydraulics, and computer aided design.
That's my opinion. and I'm glad there are those of you that disagree and happily post pics of your work! Keep it up!