Membranes have their uses but I avoid where possible. Overgrown allotment sounds a good place to use e.g. mypex, though its expensive.
The biodegradable membrane lets enough light through that perennial weeds keep growing underneath, more slowly but they survive. I think its designed to keep annual weeds at bay.
Also I have not seen much evidence of it degrading, I suspect this takes a long time, and it looks unsightly while doing so.
