Nice topic!
I think X-0 is overpriced, but not overrated. His most valuable contribution is being a heavy hit that you can't use ability DR on. That combined with his clan's pill recovery makes him a deadly opener -- you can't just ignore him, but if you pill too hard and he turns out to have been a bluff, you're in big trouble.
I think
Arkn is overrated. He is in almost every way worse than
Z3r0 D34d, and I can't for the life of me figure out why he's banned... Especially now that
Draheera is gone, and there is less reason to run mono
GHEIST.
I also think
Bogdan is overrated. His high power and SoA just seem to scare people a bit, but let's face it... Unassisted 8 power is not impossible to beat. I think that
Grudj,
Olga, and even
Baldovino are harder cards to deal with, because they can secure a 1st round win without handing your opponent a large pill advantage.
Bogdan is just a shot in the dark that you have to hope your opponent doesn't read.