I run 10 boxing on a similar system x2. Ram and video card makes alot of difference.
I do have 8 Gig ram but video card is rather old (Nvidia gf 8500) on both machines.

Sure you cant run all graphics/ shaders on max. I have 4 toons on lowest and my main window a bit higher then mid settings. i get about 30-32 fps on active window but in Dalaran it drops to around 15-18 fps.

So in my opinion its playable on this system, how ever if you want good performance then i suggest you bring out the big wallet. If its worth it is all up to you.