Personally I prefer to see two strikers rather than one where ever possible. Best and Ba have both played very well so far, there is no reason to change.
I think it would be daft to change a winning formation too much to fit in a bloke who, talented as he might be, has barely played for more than a year and before that was sat on the bench at Marseilles.
Having said that I'm still hoping to see him get half an hour off the bench on Sunday, and its highly probable hes the most talented player at the club. As you said, a bit of a dilemna.
What is the interest of that comment ?
Ben arfa is twice the player Best or Ba could imagine to be...
If he's better than them, then just play him. If you don't try another system, how would you know that it won't work ?
And you've seen loads of both, no doubt.