I have used DC extensively for long-haul premium travel for the family using Cash & Miles and only using miles purchased outright to a family account plus some credit card spend. I don't think we've bought longhaul tickets outright for years, so in our case too DC has been absolutely fantastic.

I appreciate that there is nothing comparable out there but that maybe US Airways has the programme that gets you further in terms of buying miles (with their frequent 100% bonus on purchased miles)? It'll take us a lot longer to buy our way to C class tickets for the family though... Would you agree with this in terms of burn rates per $?