In the 41st Millennium there is only...bunny hoping.

The "jump" mechanic should be stylised for the different factions in my opinion. The space marines and traitor marines should roll, Eldar should be able to jump and Orks should do sidejump. If all the factions rolled, it would seem ridiculous. Imagine an Ork clumsily trying a roll and failing mid-roll.

We'z Orkz dun' need ta jump! You'z feet need ta be were they are meant ta be: on da ground! Dose who fink we do are a bunch of Stormboyz or Flyboyz who 'ave their 'eadz too much in da kloudz!

Totally worth it.

I think vaulting and rolling for most races is fine... I think eldar should do a bit of parkour like if they run at a wall they run up it a little and can hit a button to backflip off the wall and instead of doing a simple vault they jump it while it still functions like vaulting.. There's ways they can do it so that a race aesthetically looks way more agile and feels more agile by slightly speeding up the animation without giving them completely different mechanics. I think the best example of this I can give is Dark souls load differences... Think the standard roll when under medium load as the standard dodge for sm/csm/ork and the dodge while under light load as eldar there's a distinct feel difference but the mechanics of both are the same just one is slightly faster then the other.

Also I can see some unit types having the ability to jump like the banshee comes to mind but as DJ pointed out that devastator has no business even attempting to jump with the load he's carrying.

And what grom said each race could have different animations for dodging and vaulting to kinda give them flavor.. Space marines doing tactical rolls *chaos would probably share this* orks jumping in the direction they dodging but having the same exact effect as the roll.

Wait csm and sm could have one marine on one nee to give the other a boost up hmm