Originally Posted by superscot

For sure - but that's not why one does MRs for miles (rather than status). If you can earn miles at, say 2c per mile (and I, for one, wouldn't consider that a good earning rate) you can earn earn enough miles (100k using AA Aadvantage programme as an example) to fly in F from UK to South Africa for $2000 spend. BA are currently selling these tickets for $7000 and upwards.

If you can get the cost per mile down to 1.5cpm (which is my personal threshold for a MR) the value gets even better.