As Mrs Efin and I are currently planning our trip to the US using our Amex voucher, I was wondering if it's possible to book in one class one way (F) and a different class the other way (J). We're currently sitting at 136000 BA miles, so about 24000 short for F both ways, but well over the 100000 for J both ways, and by my calcs 125000 would be the miles required for a F/J trip. Basically, we want to experience F once in our lives (as there's no chance we'll ever afford a bought ticket in F), but dont see the point of F on the return leg when we'll basically just want to sleep. Therefor, we figure F on the outbound leg - get to experience the F service both at the lounge at LHR and onboard, then snooze in the more than acceptible J on the way back.

Can anyone confirm if BA lets you do this with mileage bookings?