Wool shirts work well for me too. I have some Icebreaker shirts that I really like. When it gets very humid and I sweat a lot while hiking the wool is great because it still smells nice. You can wear it for days without washing and it still smells nice. NOT TRUE of synthetics I can tell you.

I haven't had a problem with shoulder straps causing undo wear on the wool shirts. I think if you have a problem with that you may be carrying too much weight in your pack or be carrying too high a proportion of the weight on your shoulders as opposed to your hips. But there may be other factors as well and YMMV.