I have done wooden sides twice now, I replaced them, the first time they rotted, with scaffold boards, they too have now rotted and so I have dug them out and the damp-proof membrane I put under them (which didn't inhibit rotting as it turns out). Apart from the cost of wood, something else putting me off is that, when I tool the boards up I discovered they had been excellent pathways for couch grass and bindweed.
I shall keep the same size of beds, so that I don't have to stand on the soil - one of the major reasons for raised beds - in this case I can achieve that by keeping them about 1 metre wide, so they can be reached into from either side.
Here are 2 photos of the now dug out beds and one in the greenhouse of six containers of potatoes (I couldn't of course plant outside).
|Beds gone, path remains|
|6 different varieties of potato in containers|