Melchett,
I'm not sure that commuting is tax efficient, at IPP at least. I seem to remember when I left a few years back and was doing the calculation, that commuting gives you approximately the same as if you were taxed at 40% on a non-commuted pension. Therefore, if you were expecting to go into a low paid job, or prolonged retraining (and could be sure that you would live long enough to reap the rewards of your pension) then commuting may make the sense you imagine.
Benefit of commutation is better a bird in the hand than two in the bush!