Unless it turns into a major drama I lean in the direction of letting it be sorted out amongst the voters. That said, I'm generally against it, as I am against anything that could result in people's votes going towards something that they didn't actually vote for. I think it's preferable to create a variation of the plan, and if that new plan doesn't attract enough attention to overtake the original, then that's a valid result that should be accepted, not a flawed result to be bypassed by editing the original. This thread has managed some major swings in the vote when it has turned out to be necessary, so I don't think voting inertia is so big a problem that voter agency needs to be sacrificed to overcome it.
Can't there be some system in place to notify voters in event of a plan change? Maybe a post pinging them and informing them of it?
I'm generally against mass pings, and IIRC the site mods frown upon them too.