I had 'real nappies'. The covers did last and i was happy with the fit for my kids, especially when they were toddlers but you never know how they are going to fit other children IYKWIM?
They worked well and were a good price. As i collected more nappies i used them less, as they were bulkier than bamboo or hemp. But they washed well and dried well and i really never had an issue with them. I often used the real nappy covers with other inserts.
I still have 4 of the prefolds and use them when i steam mop the floor. They are still going strong.

Congrats on your twins.