I love Kroos don't get me wrong, but i believe signing him will just disrupt your side and the balance will be all out.
Bale---Benzema---Ronaldo, they are sure bets to start that only leave three spots and Modric and Kroos will play for sure.
The remaining spot will either be covered by Alonso, Khedira, Di Maria, Isco etc. If Alonso plays there is no Starting spot for Di Maria who was your best player whenever i watched your side, except that Di Maria, Modric and Kroos or Isco, Modric and Kroos will be very weak defensively. How do you think you will lineup with him in your side? .