Yes, it does protect more a bit against slashes and acid a bit technically.
Medium:
EOD:
By saying “it is only good against bullets and explosions” I did not mean that it is worse, or equal to medium armor. It is slightly better at that. Could have confused you with that, sorry. As I mentioned previously:
In terms of difference between “medium” and “mediumhigh” my best guess (basing it on wiki a bit) is 5 armor “points”. How armor work in CM (according to wiki) is making gorilion math equations, but to simplify it, xeno slashes and acid have no penetration (only some abilities have), so you can assume that it is around ~10% damage each armor “tier” (tier are 5/10/15/20/25 etc).
That is what you get. ~10% less damage from acid and regular xeno slashes. In addition you are slightly less likely to have IB/facture/organ damage in heavy armor than in medium.
But you trade all of that for speed.
You could also notice from this very thread and data pulled from github that armor covers only chest, groin, legs and arms.
Xenos know that, so they aim feet/hand. Most of the slashes land on bodypart they aim. Which in marine case is always the same “mediumlow” gloves and “medium” boots.
In CM damage accumulated on a bodypart spreads on those directly connected to it and this damage bypasses armor on that bodypart, so xenos slashing your already wounded hand do damage to your arm that is covered by heavy armor, but has no effect in that case.
That is what you are not actually surviving ~10% more slashes in heavy armor compared to medium.
Unless it is a unrobust xeno who leaves the deflaut state which is aiming chest. Then that ~10% still doesn’t matter much, because if xenos were forced to aim chest only, any marine would be incredibly tanky in comparsion to what we have now.
If RNG favours you and not xeno, then you can survive A LOT of slashes, but if RNG favours xeno and not you, the armor you are wearing completly doesn’t matter.
What always matters is speed.
But now I am looking at B12 armor stats directly pulled from github.
B12 has the same melee, bio and internal damage protection as heavy armor, but slowdown of medium armor and additional storage slot. As mentioned B12 is superior robust choice when it comes to protection above speed.
Which means that that the only redeeming qualities EOD armor has is bullet and explosion protection.
Which sometimes can work against you, in case of you being capped on a frontline, fellow rines have a harder time killing you before you get dragged away.
Because of bodypart aim RNG and bald xenos who don’t use it, you could have a feeling that heavy armor lets you tank few more hits.
This is why heavy armor is antithesis of being robust and B12 is competent marine choice. Robust marines pick light armor for speed.