would it be interesting if you could choose to play as Isaac or Carver in Dead Space 3 Solo

I think it's a pretty neat idea to be able to choose between Isaac or Carver at the beginning of the game. Similar to how Resident Evil is with being able to play as two different characters. Depending on whom you decide, they get their own unique quests, and you're able to see things through their perspective.

Maybe they can have their own unique abilities. For example, Isaac requires less crafting materials to craft weapons and has more upgrade slots. While Carver does more damage with his weapons and reloads quicker.