Im my opinion, using cuben fiber as a footprint is only waste of money. Firstly, it could get damaged under the tent and then will leak if used for rain protection. Secondly, if you say it should protect the tent from mud, I do not find it useful as a poncho once it is covered in mud (at the moment of packing your tent and putting the poncho on).
I can see it from other side: full featured poncho, that can be occassionaly used as a footprint. Personally, I will not do that, because I wouldn't want to damage my precious poncho from quite fragile material.
If the conditions really require it and I needed to have my tent clean, I would take lightweight plastic sheet. It is cheap and can be replaced when it is damaged too much. But I still thing this problem could be avoided by better selection of your camp.