I would really like to hear reasoned arguments against it- I can't think of any that hold water.
i would jump to the “Trump Political Party with the other thirty members of my immediate family...End Of Story!!! Case Closed!!!
Yes.
Yes, I would join, initially as a protest against the perfidious Republican party and its complete lack of principles.
I might make it permanent, if the new party could show me a strategy for a dismantling over time of the old guard. That plan might include losing a few elections, IF there is a positive direction toward dominating.
If the plan is just to be disruptive and reactive, no thanks.