btw here is a list I found on reddit on what's been tested so far: "keen scout/focused breathing and stomps do not stack. mida does not stack with keen/focused breathing." from what I understand if something only increases sprint speed it doesn't stack with another sprint speed boost. it seems things that boost base movement like mobility does (walk speed jump height) stack in most cases. And if an item increase both what stacks will be the mobility part with whatever else you're combining with it but not the sprint speed. Just an fyi I was able to confirm mobility only increases walk speed (which benefits strafeing) and jump height of your normal jump class jump is un effected.

Mobility does not increase sprint speed now far as i'm aware. I don't have stompe's. But I do use my arc strider sprint speed increase in the bottom tree to stack with quick fang's en garde boost. Or either to go with the movement bonus you get off of a dodge with dragon's shadow chest exotic. Stomps and mida should stack. But I think only for your walk speed and not sprint speed. I forget which one mida boosts. either way. I haven't seen anything that goes against stacking movement wise yet.