I really liked the touch that he wouldn't remember anything after the energy went into his hand- it makes sense, but not something I would've actually thought about.

That was an important factor for me. After the botched regeneration, the energy that became Ten II just waited until Donna interacted with it in a non-conscious state. He wouldn't have any way to know what his counterpart had been up to while he was in the TARDIS with Donna, also, so he missed Davros's tirade. (A good thing he did.)