100 feet range Knockdown on a mDPS = lol:
- in 1 vs 1 situations it makes it almost impossible to kite a half brained marauder on a magical DPS/healer class, as he will disrupt + 3 second knockdown sooner or later
- in grp vs grp or mass pvp situations you likely get a lot of disrupts because some magical damage from random AOE thrown around or some noob healer trying to "kill da marauder" with his low intelligence value (same happens when said noob healer is joining a 1vs1 situation

)
Even with high intelligence reducing his disrupt chance, the mara has the possibility to easily spec for some real* disrupt values:
http://waronlinebuilder.org/#renown;000 ... 3000000000
* "real" because additional modifiers to the disrupt chance (besides willpower) are not reduced by intelligence. So for just 10 renown points you get a guaranted disrupt chance of 12%.
I'm not saying that range knockdowns are balanced across the factions, but the marauder 100 feet knockdown is very valuable in the hands of a decent player.