Sounds like a decent idea.
But just FYI the watchlist can be great for this too? You automatically "watch" topics that you replied to. Then just "unwatch" topics that are not interesting anymore?
I know. I use the watchlist too but for me it something for more important posts. I use the watch option on a post rarely. And that's because half of my new replies page is filled with old and now irrelevant to me posts I once replied to.