Going magic stalker build just like going DEX stalker build has its ups and down.
Magic:
1.low dex=lowered strip rate, so what does it matter if you're fighting a high dex class? you'll most likely never strip them anyways and if you do, its not for long).
2. sure you do high damage, but then comes gtb and they pretty much just t bagged you. deal with it.
3. you're not meant to be a dominant pvp class. enough said.
4. you excell as a party member (you force gtb and or strip if they dont have fcp resulting in easy kills) thats you're roll, deal with it.
Dex:
1. pneuma fucks you. enough said.
2. you dont have very high damage. but you're also very evasive.
3&4 are basically the same.
obviously there are more ups and downs (just like every other class). and just because one player can counter you doesn't mean that every player can do the same.