Point is, of course, at least it'd nicely handle any character code (0,ff, fff hex or etc)
Thanks before
Depending on size of the pdf, you will want memory efficient software or those that have a trick to handle large files, especially doing large sections of find and replace - which depending on what you want to do, that might be the real test.
I know I tried what I could and ended with about four different editors depending on what action I was undertaking. I no longer recall what hex editor I used for simple find and replace and can't recall the singular one that actually worked with half page find and replace text - it may have been ultraedit.