I was thinking about getting an Incase or Speck case for my 15" 2011 MBP but am worried it might make it overheat. Does anyone know if it makes temperatures worse? I do tend to do some fairly heavy computing in VMs so it will be working hard as it is. I see Incase now do a perforated case that is supposed to help with heat dissipation, anyone got one of those? Thanks.