Midfoot cleat experience?

[dogdriver]

Hey all- I'm recovering from a blown Achilles tendon and have recently started riding a (real) bike again. I'm using flat pedals, as the position of a cleat under the ball of my foot requires too much calf and Achilles tension for now. I'm intrigued by the "midfoot cleat" positioning as a means of using an SPD pedal in a position that doesn't place too much tension on my still-feeble Achilles:

http://www.trainingbible.com/joesblog/2009/12/how-to-modify-shoes-for-midsole-cleat.html

Any experience with this?

I'm looking at modifying a pair of mtb shoes (to get the cleat position aft about 1.5-2 inches from its current rearmost position) and using SPD's on my road bike, as walking in an mtb shoe is working better these days than walking on a road shoe with the cleat sticking out below.

Thanks, Chris