I'm much happier with my current system - thin A4 magnetic sheets backed by thick card, stored in a couple of plastic Really Useful Boxes. The boxes need to be strong, so the plastic ones are ideal. They are very heavy, but the beauty of this system is that the boxes have permanent homes and I can easily flip through to find the sheet that I need, removal and putting back are fuss free.
To make it easier to organise, I added header tabs to some sheets, as you can see from these step by step pictures. The scalloped tabs are made from Kanban mini scrap book pages, cut down. I used a hand held label printer to label them.
The system wasn't too expensive to put together and it's really easy to slot in additional sheets where needed. I started originally with a 9 litre box (the pink box below), but had to expand as the sheets were getting too tightly packed to flip through easily. The second box (above) is 19 litres - same footprint but higher sides, which means that I could put the box lid on if I wanted.