When you put a lot of time and effort into adding code in all the right places to provide for functional, helpful debugging, tearing it all out afterwards is just going to make you add it back in again when debugging something else down the road.

Even if you tear it out, it's way more work to try to pull it all back out, line by line, and re-implement it than to comment it out and leave the actual debugging statements in #ifdef blocks that the pre-processor will pull out anyway.