One way I've heard of to solve that problem is 45/45 and 10% to a mutually agreed upon third party (a mentor, say) who can (and has what it takes to) break those ties. I'm sure there's a bit more contractual magic to make sure the third party doesn't just sell off their part, and some people may balk at just giving away one tenth of their company. I would argue that if you're worried about 50/50 splits pulling your company apart, it's worth that small number of shares to keep your company going.