People often overestimate the influence of the GPU on day-to-day computing. Where the high-end models really excel is the creation of complex 3D scenes used in the latest games and some specialist applications (e.g. large CAD models). If these applications are outside your usage scenario, buying the 295 model is basically a waste of money. The 290 model is absolutely OK for the usual desktop needs.
My iMac with the 290 runs perfectly well for my (non-gaming) purposes, and it runs cool and silent nearly all of the time. Some people are complaining about "horrible" UI lag and stuttering when opening Mission Control, but honestly I never noticed it myself.