To start with lets compare the stats, PMV to left and APC (Armored Personal Carrier) to the right:

• 64 vs 62 strength, a strength advantage to the emblematic unit is to be expected but an increase of just 2 strength is not much.
• Range 6 vs 6, no advantage to either.
• Speed 8 vs 8, no advantage to either, but PMV all terrain trait help here.
• Special ability: All Terrain (Ignores all terrain movement penalties) vs Suppression (The targeted Unit cannot move next turn, and get -5 Strength). I think Suppression is the more useful ability, the debuff to strength is massive and its ability to make range 4 units such as rifles unable to move allow you to destroy them without receiving any fire back. Sure the increased mobility can be useful, but the APC is already pretty mobile without being all terrain.
• Industry cost 7400 vs 3700, this is the main reason why PMV is worse than APC, +2 strength and a questionable trait switch don't justify paying twice the industry cost per unit.
• Resources, tech requirement and upkeep are the same so no reason to talk about these.

• APC cost increased to 7400
• PMV gains suppression

Well if the devs do check this thread out i can also confirm the same for the the Russian EU the Cossacks. However with the Cossacks it's a lot simpler all of the sats are the exact same. Except two things.
First the Combat Strength of the EU ist 2 lower then the regular Dragoon it replaces. 44 on EU vs 46 on Regular

Also the Cossack has the unique ability: Multi-Move: Can move until all Movement Points are depleted, ignoring zones of control

While the Dargoon has the ability: Move and Fire: Can perform a full move after making an attack.

Now unless i am misunderstanding something massively, the Dragoon has the better ability and is the better unit overall.