I have recently become interested in getting a few of the Materpiece toys and I really can't decide. The ones I am interested in most are Ultra Magnus and Prime. I might get an Ultra Magnus and Prime regardless, but which Prime should I get? The Mp-04 or MP-01. The 04 comes with the trailer but the 01 is cheaper. I haven't decided if i would open either of them. Most likely I would take the Ultra Magnus out while keeping the Prime in box as they are relatively the same toy. Is the 04 better articulated or is it just the trailer that's the difference?