I love my mohair girth and my horse will second that. I think it has better grip than, say, a neoprene girth and it has a little bit of extra give. It also wicks moisture pretty well. When I bought mine, I'll admit, I bought it for the price, but it turns out that I liked it more than any of my other girths. I was also worried about it stretching out, but I haven't had a problem with it at all. I say go for it!
ETA: My horse likes this girth, too. It doesn't rub or seem uncomfortable for her at all. :)
One man's wrong lead is another man's counter canter.
"Adjust Your Pleasure"
2006 Medicine Hat Paint Gelding