I'd be way more comfortable with Upton.
Where are you guys getting Upton from? Are you just pulling this out of thin air?
I love this stuff!
His UZR/150 based upon 5000+ defensive innings in RF is -3. That suggests he might be expected to be something like a -10 to -12 defender in CF.
He's probably going to be projected to be a .360-.370 wOBA type bat.
So assuming he played 600 PAs in CF, he'd be roughly +26 runs above average offensively versus a generic league average bat, he'd get +2.5 for doing it in center, and he'd get an additional +20 for the difference between replacement and "average".
So the Reds would be looking at getting a 3.5-4.0 WAR player if they traded for Choo and stuck him in center and he played without significant injury.