140mm 1200 vs 120mm 1300 fan

[lukx]

Ok I'm thinking about changing 120mm fans in my case to 140mm I want to buy Noctuas but not sure if it's worth it. Does 140mm 1200RPM will push more air and be quieter than 120mm 1300RPM? I have Obsidian 550D case and there are those dust filters with small holes in them so I need the power to push air through. So I'm not sure if slower bigger fan is in this case good idea.

 

[Verass]

This should help
http://hardforum.com/showthread.php?t=1725851