Definitely can't run it without the cluster. I've tried to start it without the cluster just being stupid before while tuning things. Generally makes me **** my pants that I totally busted the bike, then I remember to plug it back in.
And yes, if you flick on the power while the cluster is off you get the 1609, but you can clear it easily with an OBD reader. There's no actual error, just means that it was trying to communicate and couldn't, because the cluster wasn't there.