I once did, but I prefer reforming the states, because it has much more content. The Nevada Route could be very nice, if you want to play in Multiplayer and maybe don't instantly kill off your friends and maybe even cooperate with them :)

I have on several occasions. Sort of amusing to see the Shi become the NCR faction leader, but it's pretty much a disadvantage during the game because the AI is dumb and you're stuck working with them with less resources. All you really get out of it are a few free cores, and the focus for adding Deseret doesn't work properly.

Honestly the Nevada route is more about having the opertunity to get a friend to play as the NCR Desseret etc.

It's pretty sweet I'd say. You get to form a new United States and you can invite some powerful members into it such as the NCR, Texas and Oklahoma? Forgot their name. You get to make quite the arsenal of liberty

I'm going to suggest that a future update of this submod include a generic focus tree for newly reformed states. In my most recent game Arizona couldn't handle its own resistance.