I run 6/4 splits pretty regularly. There's a 1/200 chance of getting resource locked out the gate. I'll probably get screwed at some point, but it hasn't happened yet.
but then you have the Times that you draw 3 of your lesser affiliated objectives and 1 of your main, so your stuck with a single resource for your higher represented faction. not an auto loss as with being resource locked, but can certainly put a damper on things. I was running the smugglers cavern deck for a while and I would get 3 S&S objectives and a single Jedi objective pretty regular and that really hurts when you need to put out multiple Jedi units/enhancements/events and only have a single resource.
having said that, a 6/4 split is acceptable, just be prepared for a tough game every once in a while.