There's a very lengthy thread on the downgrade of *G baggage allowance over on the UA board on FT. Might want to check there for experiences and strategies.
My quick check of the baggage calculator on the UA website shows transborder (Canada < > U.S.) is 1+1 bags, and domestic U.S. is 0+1 bags, for *G.
Thanks. I will have a look at it.