I'd like to see some more information about the local setup, including hardware and the postgresql.conf. Otherwise, this tells me very little in terms of comparison.
In anyway this test won't tell you much, just how different systems behave to bigger load. The local setup was quite usual: PostgreSQL 9.2, Mint 13, default conf in VirtualBox in iMac i5 12GB. (read: home computer, no tuning) For me the result is that mostly RedShift is on par with local PostgreSQL, sometimes even winning for Also the big deal was that RedShift scaled linearly.
The default Postgres configuration is pretty weak. work_mem is set way to low, for instance, and that's bitten me a few times. I wouldn't say it's unrealistic--lots of people run with it that way in production and never find out how easily they could speed things up. Even me, for years.
But ultimately I'm more swayed by your interaction with it and I hate the endless benchmark tweaking that comes after every blog post about performance testing stuff. The point of this Redshift thing is hugeness first and foremost, so it's interesting.