Democrats would be hurt in the electoral college but would get a big boost in the Senate. I like this plan.
I don't think it's very realistic anyway, but it seems awfully short-sighted to evaluate this plan based on things like how many Republicans or Democrats it might add to the congress at this time, given current voting trends. It seems to me that the economic and ecological realities of the region should be taken under consideration foremost. Water rights is the first thing they would probably have to sort out, and that wouldn't be easy. Also, there's higher education and medical services and taxes. The system was built on an earlier model, and just drawing lines in the sand and naming new capitals in some grand gerrymandering scheme isn't going to solve any of the state's problems.