It's pretty clear that size is dependent on what you are used to seeing on your wrist..
Rolex dials stay pretty consistent in size even though the cases differ greatly.. There is not much differenct in the dial size on a DJ or a Sub.
Omega at 41 and 42mm is not a significant step up in case size, but they tend to put a larger dial so they appear to 'wear bigger" if you are used to one size.
But look around. Most with a SMP on do not appear to be wearing a 'bigger' watch than your Sub.
As for the EXP II...It also has the typical Rolex dial and crystal size, but the shape of the bezel makes it appear to be smaller. However, it is that shape that make it less prone to bang around than the Sub or the SMP, and that makes the EXP II my daily beater.