I can (and would) opt out of taking my phone to China. I can't easily dodge US' requirements.
These two bully super-powers really give me a bad feeling about the future...
Leaving a posh phone at home to take my old phone I could do without moral complications. I could even say I left my posh phone at home because I didn't want it lost/stolen on my travels. That would not be lying even if the real reason was that I didn't want it violated by a customs officer.