I made the switch from AC to bmi. It was a wise move for me. Most of my flying is actually UA when I pay, and whomever when I cash in award miles. bmi's earning for premium classes matched LH's, but you don't need 100K for Gold, and the cash and miles is a wonderful option.

While I have no need for the upgrade vouchers with bmi, I have so far hung on to them, as you may never know when the time will come that I will actually be back on their metal.