2008 Prius?

I have been looking at buying a Prius. I looked at the new Prius (generation III) and was impressed and loved it but found I could buy a demo 2008 Prius (Generation II) from the same dealership for $16000 (Australian) less than the new model. The Generation II only had 20000 kilometres on it. Most of my use of a car is for a 70 kilometre round trip on rural bitumen roads to work each day and a 400 kilometre round trip on highways every third weekend to visit my kids and grandkids.

$16000 is a massive price difference and my first thought is to buy the demo. However, comments made in this forum have caused me to be concerned about buying a Generation II model. The comments range from it wanders on the highway due to wind effect, that the Generation III is definitely a better highway cruiser, that the driver's seat in the Generation II is very uncomfortable if you have to sit in it for any long trips, that the Generation III has significantly better fuel consumption (disputed by others), that "the cooling pump for the high voltage inverter system tends to fail on some.....starting at about 60000 miles, causing a power loss and potentially expensive failure of the inverter power unit", that " due to the added complexity of the hybrid drive train ..... very high costs have been reported on a few of the older 2001/2002 cars (some up to $8000 US). I would be hoping to keep this car for at least 10 years..Should I be concerned about buying the Generation II demo?