On the whole I'm not a fan of using cfincludes within a cfc. However, Hal Helms pointed out a great use for this with class based mixins. There are definitely downsides in terms of it being less clear what methods the component contains just by looking at the cfc but there are definite use cases where class based mixins can easily solve problems that would otherwise be difficult while staying DRY.
Even worse than cfincluding functions though is the idea of cfincluding a chunk of script into a cfc method. I did it with my programmatic config script for LightWire and have decided that Jared (and everyone else) was right - an XML config file is a better solution and I'll be implementing that as soon as I get a chance. But I've come up with another use case for a cfinclude within a cfc and it has to do with rendering components . . .
[More]