It is an interesting proposal that can work if there is a very clear vote and hence valuation one way or the other. Where it can get real messy and problematic is if there is close to an even split or even significant vote for the minority chain. Then the uncertainty created can cause a significant overall loss of trust. The reality is that a hard fork only works with strong consensus and my thought is that Peter R's proposal will expose that reality. Having said this it may in the end have to come down to a spin off method solution as a last resort.

Edit: The best solution is a hard fork with strong community consensus.