Eh, I'll take a Ghost Sniper, which over the course of the game will do on average about the same amount of damage, and is more flexible.
Not actually more dangerous, I worked out the average damage model for MHA and Manhunter/Narn, Average damage is within about .5. Manhunter/Narn gets two attacks at MAT 8 to hit, but if they miss with eiher (especially charge) their damage is a good bit lower. Downside is that an assassin has one attack, but with 4.5" more threat (c'mon people say models are trash compared to others when there's only 1.5" in threat difference) they can more reliably threat targets and get to swing against what they want more often. Also the Assassin gets pretty far ahead of a manhunter in a damage race against targets with Shields/Bucklers/Spell bufs.
But really, most casters in their right minds try to avoid or kill MHAs as fast as possbile and with a 14" threat that either means devoting a lot of resources to try and out-threat them or keeping your caster further back than many would like.
And if you look at all of that and say "I'm not sure if that's worth 2pts", the game you're playing is miles away from the game I am.
Also not being engaged after the attack