Just bought the iMac 27" retina 5k with the 27" Dell 5k today and since there is a huge price difference in Europe with the iMac priced at € 2896,- and the Dell at € 1091,99 I think I made the right decision.
Can You tell more about your setup?
How smooth behave OS on 30MP resolution? Do you have some problems? Do You hear vent in the middle of the work like surfing, playing youtube chating etc.?
What CPU usage you have when do things like this?
Thanks for reply