I don't like the concept of playing two lefties at the very beginning. It should be a combination of both: a left hander and a right hander. And this applies for all 3 formats. You give the opponent's bowler less chance to settle with the bowling line and length. So, I would prefer Tamim and Anamul or Tamim and Jahurul.
I still don't get why Imrul is so important for a lot of us. He is nothing but a 'khocha' master in all formats of cricket. He is also utterly confused with his role as an opening partner of Tamim. The underlying reason for the success of Imrul/Tamim pair is only Tamim. If Tamim continues his slow start (like Asia Cup) in future, that pair is going down to drain for sure. Imrul usually waste so many balls just to give strike to Tamim - who is usually in a mood to thrash the opponent. I personally believe, imrul is not a national team material and well suited for 'A' team.