I will, depending on the CTO. Since my topicals are a mix of mint and used stamps and I'm really only concerned with the subject matter, there isn't much of a difference between a postally used specimen and one that's been CTO. It doesn't adversely affect the subject matter, it's not a big deal.
Nells250, when it comes to topicals, I collect mint, used and CTO stamps. It doesn't matter because I just enjoy the subject matter and like to view whatever stamps exist for airplanes, zeppelins, ships, etc.