To me 5000 lines of C code is a LOT of code. Linus's first release of Linux was only 10,000 lines of code. Given much higher expressiveness of Lisp, I think 5000 lines of List code is not all that to boast about. I can't pull a reference here but according to one of the studies, the productivity of some of the well known programmers was measured at 10K LOC/year (yes, it's very loose measure of "productivity"). So writing 5000 lines of good code may require ~6 months, i.e., not a trivial amount of work. Although I agree it is cool to have X server in Lisp.