It's all about legs: check out my video review of the Forgeworld Mk 3 and Mk 4 Legion armor compared to the normal armor sets as I try to figure out how I'm going to create my Heresy-era Army.
Here are a few detail pictures. In each, the new Legion Mk bits are on the bottom.
Completely different backpacks for the Legion Mk 4, and much better.
A nice variety of helmet designs on the Legion Mk 4 set, as opposed to identical helms on the normal set.
A few nicely detailed Legion set legs, but I really like the running legs from the normal set.
Five matched sets of arms on the Legion set; dimples on the inside of the shoulder help you match up which goes with which. The Legion legs also sport corresponding dimples.
Not as much a variety on the torsos.
Shoulder pads are identical, except for attachment. The second set of 5 for the Legion come with some variety: a studded one and one similar to the Mk 3 design.
Mk 4 Armor Verdict: the otherwise superior Legion set only lacks the dynamic running legs.
If you didn't know the normal set was on the top, it would be hard to tell which is which.
Really nice details on the Legion Mk 3 torsos.
The backpacks also look identical...
... as do the helmets.
Like the Mk 4 Legion set, 5 matched pairs with dimples for easy pairing.
Shoulder pads are identical, but with different attachment points.
Mk 3 Armor Verdict: Get both Legion and normal sets.
Anyone have any experience with the Mk 2 and Mk 2 Legion sets?