I've just booked two one-way economy tickets from Munich to Heathrow. LH does not sell discounted one-way tickets on peak AM flights so miles are a sensible choice here.

Mileage required with BMI (all miles): 9,000 for 2 pax
Mileage required with BMI (cash and miles): 4,500 + £40
Mileage that will be required when DC becomes M&M: 45,000 !!

Just a polite reminder that if you are planning a redemption in 2009 and have not yet booked it, you have nothing to lose (except the £25 change / cancellation fee) by booking it before the LH takeover goes through in early January. Whilst the risk of LH jacking up redemption rates or scrapping cash and miles on Day 1 is relatively low, there is NO WAY that LH is going to allow a situation like the one above to continue for long! I may be wrong - I probably will be - but don't be under any illusion that you are taking a risk by not booking redemptions before the takeover date.