Another solution is to keep the boots and buy a pair of waterproof socks.
You say that the boots are light and comfortable. Carry a pair of (say) Bridgedale Midweight Storm Socks in your backpack and you can put them on when waterproofing might be needed and your feet will stay perfectly dry.
Other benefits are that in warm weather you needn't suffer hot, sweaty feet, and that if your feet should get soaked for whatever reason, your lightweight boots will dry out relatively quickly.
My wife has been happily using this method for years because she loves her comfy, but leaking, Salomon boots and doesn't want to change them and she certainly wouldn't want a pair of leather boots. My Scarpa boots nearly always keep my feet perfectly dry, but I carry waterproof socks just in case. However, I rarely wear boots anyway, because I much prefer the comfort and freedom of trail shoes and will only choose the boots in extreme cases.