I find it does however.
Why install 50MB of requirments just compile and install something that would easily have fit into 1MB of converted packages? Yeah, there are some exceptions to the rule and to get optimized packages requires some package hacking, but generally it's faster than compiling something with a lot of requirements not in the repository.
For example, converting the manaplus tmw client (from scratch with all it's dependencies) originally took me 10 minutes to do. Compiling everything it requires from scratch took me 2 hours and then 15 minutes every time I wanted to upgrade it. Now if I want to upgrade it, it takes me 2 minutes to do. Hence it's faster and saves effort.
Anyway, getting off my high horse now. I would rather recommend converting over the debian package for the simple reason that debian has some weird naming conventions for some of it's lib files. Here's the method I normally follow:
1. Find the Debian package I want and convert it and all it's logical requirements (most debian packages are split in two or three files - normally named something like package and package-data). Install it.
2. I try to run it from terminal. If it works, you're done. If it fails, write down the error, especially the file name of the lib it requires to work.
3. Go to http://www.debian.org/distrib/packages and scroll down until you see the "Search the contents of packages" box and enter the file your looking for. Click search and download that package, convert and install it. Then try running the program again. If it works, you're done. If not, repeat step 2 and 3 until it does. If it takes more than 5 times, then it's probably too integrated into GNOME/KDE to work at which point you should give up.
Another tip is to use Debian Lenny Packages. They're not so up to date, but they tend to work ;)