I have little experience with actually making debs (I'm a package maintainer for Fedora), but I like the fact that the spec file and patches are separate from the tarball. Makes looking at Fedora's git for questions about some quirks of some package easy (e.g., "Why is this feature missing?" to "Oh, missing configure option"). AFAICS, to get this from dpkg sources, I'd need to download the tarball and extract it. If there's some other resource than http://packages.debian.org/, I'd be grateful for a link.
Agreed about rpmbuild. I just use mock when building SRPMs for the most part.