rolandx has the right idea not mentioning relying on internal mics.
Even if they sound good, which most don't, you can obviously get better placement with externals. From what I've heard, the D-100 does have pretty good sounding internals though (probably better than the HR), if that is important to you. The only recorder that I'd rely on for internals is the Chris Church modified R-09 Micsketeer, which I often use for non critical recordings and as a backup recorder when running 2 rigs.