1. I switch to another tool if and when I have problems with my current tool. Because Pathogen has served me well for the last two years there's no reason to switch to Vundle or some other plugin manager.
2. Vundle is too heavily Git/Github-centered for my taste.
While I also wish Vundle weren't as wedded to GitHub, I still find it to be the better of the two tools. Plus, Vundle can also use the Vim Scripts repo as a source, so it's not strictly tied to Git/GitHub.
2. Vundle is too heavily Git/Github-centered for my taste.