Thinking back to the Six Nations 2011, we did manage to score trys. Even with a very, very one dimensional midfield we managed to score.
Yes, we would have done better and probably scored more with better centres, but we still managed to score.
Therefore, I don't think having a midfield of Barritt and Tuilagi would necesarrily be such a bad idea. Sure, it would be limited in a few ways, but firstly Barritt's distribution is no way near as bad as it's made out to be - he's just not very creative. However, with a back three of Sharples, Ashton and Foden (probable), I think we can afford to play a bit of front foot rugby in our midfield, as we have such flair and talent outside of it.
This kind of game plan would also be made more solid if we had Flood in at 10. He's not the best in the world, but on form he can ignite backlines.
So... for the 6N (post Italy and Scotland, when everyones getting back from injury.)
9. Dickson
10. Flood
11. Sharples
12. Barritt
13. Tuilagi
14. Ashton
15. Foden
20. Simpson
21. Farrell
22. Brown
I'm not 100% sure on this working, but I just think because Barritt is England's best 12, and Tuilagi is England's best 13, the lack of finesse or flair between them won't cause either of them to not start.. Because although I admire Farrell's acomplishments, I don't believe he would be more effective than either of them in the centres.