For me, a typical reward trip would be a short one hour flight to NYC for some shopping. So, I could live with Basic on the outbound for an hour, but, on the way back, I may need 2 or 3 checked bags for purchases I made. I don't believe it's possible to do Basic in one direction and Main Cabin in the other direction without redeeming for 2 separate one-way tickets - - so I would lose the discount when the round-trip mileage requirement is cheaper than redeeming for 2 one-ways.