Vibex power blocks vs power filters

I am considering purchasing the VIBEX power boards or the VIBEX boards with in-built filter (see: http://www.vibex.es/productos.php).

There is a lot of talk that filters "kill" the sound, or limit dynamics, or produce muddy bass. Does anyone have any experience with the difference between these 2 products (with filter vs without)? Others swear by the filter products...

There are a lot of serious companies out there producing filtered products (e.g. Purist power cables with filters and ac filter block) so the rumours cant all be true!

Any thoughts?