How are FPM-generated debs any less integrated than native packages? You have the same control over the package metadata using its flags as you do with a Debian control file, and using `-s dir`, you have complete control over the package contents. You can ship rc/Upstart scripts, use pre/post-inst/rm scripts to add users and backup data, etc. These are all the same tasks that lots of Debian-maintained packages perform.

Please look at the FPM wiki, you'll see that it offers many more options for integration than checkinstall (which I used to use, and hated):

https://github.com/jordansissel/fpm/wiki

And why would you want to create source packages? One of the benefits to generating binary packages is that you compile once and roll it out to hundreds of servers. I'd rather not have to compile, say, Erlang on every target server.