I code with a focus on TDD and small unit tests, so even though I do mostly statistical computing work, my development tests use small amounts of data and low computing power. When I actually need to run big production stuff, it goes off to the Linux box or a Linux server cluster.
My beef with the imac is that it is not really that much faster than my MBPr, but has terrible heat management. When I am running big jobs on it, it gets a few degrees off from a toaster and heats up my office. A 2.5k linux box would not have this problem and would be way faster.