What's so scary about them compared to other weapons?
The only advantage they have against any other Reach 2 weapon is the damage code. If someone has the skill to use a monofilament whip well, they could do nearly as much damage with any other melee weapon. Just put the guy up against a troll melee character wielding a claymore, give him comparable skill and Agility ratings, and... well, I don't see the problem. Even if he's relatively average Strength for a troll (Strength

, he'll have Reach 3, a base DV of 8P, and a -2 AP versus the monowhip's Reach 2, 8P, -4. Or hell, just put him up against a crazy specialized adept wielding a butter knife, but with a dice pool that's miles ahead of the monowhip wielder's. Melee is all about winning the opposed test.
The monowhip is no more 'overpowered' than, say, a Ruger Super Warhawk. Sure, if you compare it to a Streetline Special it
looks ridiculously OP, but it really isn't all that much.