Denise,
I have cut & pasted below my answer to the same topic a few weeks ago.
Hope it helps.
We have found the breathable "carpet" type of groundsheet to be very good.
Sure, they will let mud or standing water through in extreme conditions but on the more usual surfaces, damp grass or gravel, they are fine.
The main thing is that they do not kill the grass like a normal groundsheet, although the grass will lose a bit of its colour after prolonged use. They are also very comfortable to walk on, even with bare feet on a cold morning.
It is a bit more dificult to clean the underneath after you get home because the fabric is woven but I use a pressure washer or just let it dry and use a stiff brush.
We are just about to buy a new awning to fit our new and larger van and will be buying a new Bolon "carpet" to fit.
Clarky.