Well from my reading and understanding, when talking LHE rather than NL, you want 300BB for a 5% risk of ruin if you are unwilling to go down in stakes.

At 3/6 this would mean $1800 would be enough theoretically to cover you, so your current bankroll would reduce the risk of ruin even further....given that I don't think you could be faulted for going to 3/6 and seeing how you go BUT only because you have been there already and seem to understand that you should move down if you need to.

In regards to how much to keep in various places, I've pretty much got most of mine tied up in sites atm for bonuses I'm working on but that's probably not the best suggestion