Even if I were so good, why I do have much more losses in the other mods? It's really something slowing down expansion: I make an incursion but after defeating the enemy army I don't have enough forces to take the settlement. Pyrrhic victories perfectly possible.
I also use the ethnic units a lot - and here's another observation. Large availability of good local units makes factions having very good all-round armies. Again, in the other mods one may struggle with having no access to some types of troops - it forces you to employ different fighting styles. In the EBII I always had local troops fill the holes in my native roster (it might be though due to having played with a limited number of factions). In the other mods even if you do have such an access, you suffer losses and you're losing this plughole. In the EBII once you recruit one unit, you play with it for a long time.
Furthermore, with the AoR units, there're many units possible to be recruited. The long pool-refreshing times (for some units like 25 turns) make then little difference as there're some many (often similar) units and you suffer little losses.
All in all: to my mind, there are too many soldiers available around what makes the game easier (too easy? again, this might be just the experience of the factions I'd played. I'm wating for 2.35 to play Lugiones, for instance).