I can't speak to the corrosion, as I've never owned one (I just fly them); there was a thread on here somewhere about R44 corrosion, try a search.
Regarding starting, although the procedure is different, I wouldn't say either is more or less difficult, especially not if it's something you do reasonably regularly.
The Raven 2 has an extra 100lb of payload, which may or may not matter to you. It's also fuel injected, so no carb heat to worry about (or carb icing, for that matter). No idea about the robustness of the engine or hydraulics, as I've never had either fail on me.
If I were buying one, I'd probably go for the Raven 1 just for the cheaper initial outlay, but then, your financial situation is probably different to mine. They certainly feel pretty much identical to fly, in my (limited) experience.