I have mine at 1000cpu/480dsp now.

Just tried running a demo route in Sygic and while that's running, I started playing a normal xvid video using mplayer. When I go to task switcher, I can see both of them actually running.

Then I go to Conky and it shows 1000Mhz at 100% CONSTANT.
I left it like that for a few minutes. No issues so far. Nice.

TweeGo login screen now shows up 5 seconds from launch. (was 8-9 seconds at 600Mhz)