Not to repeat an answer, but I think I can add a bit more.
Slickedit is an excellent IDE.
It supports large code-bases well without slowing down or spending all its time indexing. (This is a problem I had with eclipse's cdt). Slickedit's speed is probably the nicest thing about it, actually.
The code completion works well and there are a large amount of options for things like automatic formatting, beautification and refactoring.
It does have integrated debugging.
It has plug-in support and fairly active community creating them.
In theory, you should be able to integrate well with people doing the traditional makefile stuff, as it allows you to create a project directly from one, but that didn't work as smoothly as I would have liked when I tried it.
In addition to Linux, there are Mac and Windows versions of it, should you need them.
