Who's owned a mundic house?

We were almost ready to complete on a house in Cornwall when the mundic survey results came back - all the concrete in the footings is 'unclassified'.

But if a weird situation, as after having our offer accepted, we heard a story that the house had previously been found to have mundic in one section of the footings. A local person bought it as a cash buyer, proceeded to have the mundic removed and the house was reclassified as all A1. They sold it and made an absolute killing on it: 125% profit in 5 years.

I was a bit suspicious, so ordered another survey. This has come back showing all samples from the footings as unclassified, so the house is currently unmortgageable. Stage 2 testing is underway to determine if it's grade A2, B, or C (B & C being unmortgageable).

As a general rule, grade B mundic concrete reduces a house's value by a third, so the house would seem to be very good value at that price. However, I've just spoken to our RICS surveyor about it and he said, "it's not if, but when the concrete will deteriorate. I would only buy a mundic house if I were planning on knocking it down and rebuilding."

So, I'm asking: do you agree with the above? If you've bought a mundic house, how did you justify the risk? I could end up with massive cracks in the walls and needing to rebuild the house.