I can only add that I have checked 3 pieces at 70 lbs with LH all the time (since 2007) - with the bulk of travel on UA, UA ticket and only a short feeder on LH (status 1P, later 1K). Mostly, no questions asked. Sometimes, they had to call UA. In the end, UA rules always prevailed.

I have not done this since April 1st, though. Last time was end of March, next time end of this month. From what I could gather from this thread, nothing should have changed, though.