I resolve problem with dust on front fan on 650D...
I cut plastic parts with dremel and only plastic frame stay with antidust wire.
But because that filter is not enough I keep 200mm Demciflex filter below.
Once a week I remove that and clean back side with brush and demciflex with alcohol.
Demciflex stay on grill inside and it's easy to remove if need.
And when you look from front side no way to see grey dust or plastic grill.
I would never replace my Obsidian 650D for some normal case...
NEVER! That need to be something very nice as some nice Lian-Li or Caselabs... For Thermaltake, CM, or these new plastic CORSAIRS... NEVER.
Obsidian 650D could be modified so nice... his main flaw is lack of 360mm radiator on top and too big cage for DVD. But that could be fixed. Internal USB 3.0 wires from I/O Panel could be removed and install wire from
Obsidian 350D. Hot swap bay and fan controller removed and 360mm radiator will fit. One cage for HDD removed and other could be base for watercooling pump. Case is really cool.