Hummmmm....
I bought a Raven I 9/03 and have about 200 hours on it. I have also flown another Raven II for at least 15 hours. My flying goes from the mountains near Yosemite and up north in the trinity alps to basic tours around the California coastline at sea level. Here's my general feelings:
1. Robinson makes really good, simple, cheap helicopters. Just can't find anything that touches them for what they put out. Granted, I'm sitting on a well maintained and hangered / less than 300 hour machine.... but so far I love it.
2. There is a performance difference at altitude between the 2. I notice with 2,200 lbs or so, once you get above around 6,000 ft on a reasonalbly hot day in the summer, you're going to need to slow down a bunch in my ship (Raven I). I have had mine up to 11,000 ft with one other guy and a bunch of gear but it was a constant source for concern and a good lesson in watching MRRPM.
On the other hand, going over the same mountains on the same job, over the same course in the Raven II you really can notice the difference in altitude performance.
3. Fuel Consumption - I was surprised to find that in an apples to apples comparison (again, doing pretty much the same job in 2 different ships within the same month (April 04) in similiar conditions), I was surprised to find that the Raven II got about the same fuel consumption.
4. Payload - Don't count on the extra 100 lbs making much of a difference.
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Now, that said.. here's some unsolicited stuff...
1. Get the bubble windows - Much better than the stock stuff and worth it.
2. Get the instant VSI - It's pretty nice if you really need to know exactly what's going on.
3. Don't get the Robinson cart - I like the heli-tow cart from the guys in Canada. It's smaller and cheaper.
4. Get the 9 hole pannel and an AI - Nice to have and if you ever decide to do instrument training in it, you'll have a nicer setup than the instrument trainer pannel (kinda big and view blocking).