sunn03, that sounds a lot like my time-honed 5-3-2 formation that I really like. The drawback of it is that you need insane wingbacks to make it work. They need heaps of stamina, decent passing/crossing as well as being kick-ass defenders.
If you have these, it's a very fun formation as you then attack with both wingers, two CMs in addition to your forwards.
I am often twharted in being able to play this formation though, either by not haveing the WBs to do it, or just plain having too good AM R/L that I can't put out of a job.
For this game I have had success with a continously adjusted 4-4-2, and now lately making it a diamond. I have a fast defense, and always adjust my defensive line after the speed of the opposing attack.