The Raven II is a major improvement over Raven I. I have flown Raven I for 3 years and just got a Raven II this spring. Totally different machine. Quieter (the blade end caps), more power which makes a big difference if you fly close to MTOW and the changes to the main blade have definitely improved performance. 18" hovers at 2000 ft are possible in no wind with full tanks and 3 up.
The increased payload is a bit misleading - the 100 lbs is actually only 75 because of the weight of the fuel injection gear......
Values of R44 Astros have plummeted in the UK as a result of Raven II success - and the same will happen to Raven I as soon as the new factory comes onstream at RHC and they reduce the wait time.
If you value your investment, do not get a Raven I.
But if you just want something to bimble around in for 10 years and you want to wait a bit.......go for a used Raven I once the prices start to drop.
Do NOT get an Astro.