Uh... I think you're getting the Morannon Orcs confused with the orcs from the S.E.E mod.
Just giving them higher prices and slightly higher stats is just plain boring, please excuse me. The Morannon Orcs should be more individual (*glares at Mike* No, I'm not insisting or saying that you must, I'm making a suggestion. You misunderstand me). Which is why they need some kind of individual trait, like being counter-infantry but weak against pikes and cavalry.
Having Mordor units come in groups of fives completely goes against everything that symbolizes Mordor. Just, ugh.
Otherwise, that's basically what I said. Faster than ordinary Orc spam archers, and do very good damage against almost all units except siege and buildings. Very weak when confronted hand-to-hand. If you also gave them the ability to stealth in trees, they'd be the ideal ambush unit. But because of the cost, for ordinary attacks you'd use basic archers, maybe upgraded with F.A. Giving Trackers poison arrows would also enhance their assassin-like aspect, shooting heroes and monsters and then retreating to the safety of the trees while their targets weaken from the poison.
And Trackers, well, you could say that they can only get trained at a Lvl. 3 Orc Pit / Uruk Tent, which means they'll have to be more late game and you won't be able to spam them. Maybe increase the build times, too.
This could be one hell of a cool unit, guys.
I don't play SEE, so that's impossible ;D In my version, there are normal orc warriors, morgul orcs, and black orcs; iirc morannon orcs are to be moved to the inn.
They don't need stealth very much imo (since it's much easier and more practical to just spam free orcs than to bother with ambushing, but I wouldn't really be opposed to them having the option if u really insist), and the few numbers would make them seem more like scouts and not simply better archers. If hordes of 5 are too small, then hordes of ten may be better.