I would have advised against filing your tips. Lightly sanding would have been all I would have done to the "grody" tipped 45 watt.

Why? Now that you've exposed the copper, if you're using rosin core solder, it's going to start eating away the tips, and you're going to have to keep filing them as they lose their shape and they'll get smaller and smaller. It's a viscious cycle.

At least, that's been my experience in the years that I've been doing electronic assembly.

I use pretty small tips for that sort of work though, so maybe yours won't corrode away so fast.