It will probably not make to much difference if your skill sets are about the same( unless you get trolled), it will be tight, when you say 4-3-1-2 is his midfield 3 MCs or ML,MC,MR, I am asusuming its the THE 3 MCs so a 3-1-4-2 can exsploit the space on the wings, the DMC can hold up there 3 MCs and act as a playmaker for the front 6, I play forward arrows on him!, you now have the option at some point to either take him off and go more offensive by playing a third ST or try protect a lead by changing him or a ST for another DC to go four at the back.