Robert's is quite explicit that a meeting chair does not vote. So there's that. It's certainly followed in larger meeting groups.
When I said our board members are active, I mean they all participate in the discussions and help form opinions, whatever they are. Strictly speaking, Robert's also says that the chair isn't supposed to participate, but the way we function so far, I don't see a problem bending that. Besides, even in organizations which do follow this non-bias rule, the chair regularly works with an ally before the meeting to get his/her substance into the discussion.
My comment on operational roles is aimed at the difference between board-policy consideration and hearing reports from operational people. A fine point that's only partly relevant here.
One reason that Robert's has a non-voting chair is that it is a further safeguard against an over-powerful chair. Remember that the chair sets the agenda, and controls who speaks and legality of motions. Not an issue in our current group, but worth keeping in mind.
I'm having a hard time seeing the circumstances in which a nonvoting chair will limit our actions. Any illustrations come to mind?