I prefer MTP camo, but I think the old DPM smock was better.
I find it dries quicker.
I don't like the fleece lined 2nd pockets in the new smocks - again because they increase drying time.
I don't like the mesh inner compartments (although this probably improves drying time I guess!!)
They are both really tough. I've given both extreme beatings with the Marines and now the Rifles (reserves) and they've both held up really well.
Plus, they're both easy to repair with a needle & thread.
I think the new MTP smock is slightly bulkier. Both are quite bulky compared with modern light weight hiking gear, but I'm guessing if you're after a smock, it's toughness you're after.
I did read (on here I think) someone saying that when we first switched to MTP, the smocks were exactly the same, just a different camo pattern.
I've never seen one though.
P.S.
I'm talking about the later DPM smocks with hoods, breast pockets etc.