> anyone's experiences using them in soft, sodden ground,
Well, they are going to pull through 'soft, sodden ground' a bit, but is that really what you will be camping on?
I found they gripped quite well when pushed into clumps of grass, even in 'wet' ground. I also found that a 'wet' surface does not always mean the soil is really soft further down. So I stomp on the peg (with care of course) so it is right into the ground, and have not really ever had a problem. Getting the peg back out ... well, try having a spare peg to hook it with!