Neither Sissoko nor Amos look like DM's to me. Not natural ones anyway. I know Sissoko played there a bit last season but I imagine it was always alongside Wanyama or Dier, a proper DM. I don't necessarily disagree with you, but we can't be 100% sure whether we've properly switched to 4-3-3 until Dier and/or Wanyama are available.
We played Mason/Bentaleb in a midfield two and neither of those were defensive midfielders. Its a pre season friendly, not a league game.
I'm not saying we've 100% switched but the fact we've worked so hard on it would probably be an indicator that Poch is thinking about it. Most of the top teams in Europe play 433. It suits our press. It provides us with more pace and gives us more creativity from the middle of the field.
Seems a no brainer.
Guess we won't know until 11am next Saturday.