go 27
I think 27 offers a nice improvement over 24, especially when opening two or more windows for multitasking. And based on your viewing distance, I would go with the 27 inch. You'll appreciate the larger size and won't notice any problems with pixel density at 30-42 inches.
Impressed
Not the components I'd pick but I'm impressed.
PCpartpicker lists the total for these components at $897. Only $100 mark up to cover build costs and 72 hours of testing.