I'm glad that I bought that ticket I had been dithering about on the 11th!

With reference to a recent discussion - a link I will now try to find - it was sometimes cheaper to cancel a "Light" ticket, and book a new ticket, rather than paying the change fee on top of any possible fare difference (which had recently increased from €70 to €100 for medium haul). Of course, I would not recommend buying Light tickets speculatively; it's just that a Light ticket, although non-refundable, can yield a surprisingly large refund if you cancel - and now that Light tickets issued from yesterday onwards can't be changed, your only option if you can't take the flight as booked is to request a cancellation and a corresponding refund of taxes).

We discussed this recently in this thread: Non-refundable KLM tickets

Even "non-refundable" tickets can yield quite a refund; particularly if you've bought the very cheapest Light ticket early enough, the bulk of the price paid will be taxes and refundable