Despite being a fan of premium audio cables up to a point (and no, I'm not looking for a lecture thanks, been there, done that here and elsewhere) I'd never spend a penny on any of Monsters range.
There's selling products with debatable benefits, and then there's
Monster HDMI Cable Scam | Gizmo Republic
Also, the way they market their HDMI cables in Comet is shocking. The £45/55 cables seemingly only do 1080i. Then the £60 one and above do 1080p. You want one for a PS3 ? That'll be £70 then. And if you want "ultimate" performace that'll be £80.