I think the general view, and I tend to agree here, is that Cahill does not play as well in a 4 man midfield. Sure, he has 1 or 2 decent games there, but overall, he is much more effective as the 2nd striker.
Besides, we have been on a great run of form, despite surrendering a lead on too many occasions recently. I don't think our problem is our attacking approach to the game and 4-5-1 is our best formation.
I would be happy to see Yakubu and Cahill - as both seem to be our best two scoring options.