Three 2.5" drives will fit. My main concern was before I realized the 1TB WD drive as also 2.5" as opposed to the typical 3.5". You just need to make sure it actually is 2.5" as the images I've seen show what appears to be a 3.5" drive.
I saw the mesh front cover version as well, and I'm not overly fond of it either. Even if the cooler does fit, where is that cool air supposed to come from? I mean, to me, it seems like you're spending £71 on a cooler and not giving it any way of doing what it's supposed to be doing.
There are other "discreet" options that are available to you. While many may disagree with me, I have always been a fan of HTPC cases, especially if it's going to be openly visible in the living room. My old HTPC (strictly for liveTV/DVD/Blu-Ray) set up perfectly in my home theater cabinet. It housed all my components with ease and while about the same physical size of your standard ATX case, was aligned horizontally, like an old desktop, and fit in with the rest of my home theater set up without being obtrusive.
Unfortunately, I went cheap with an NMediaPC HTPC case and the front flap didn't last long, but it still looked nice in my living room. This was my old HTPC case and my Home Theater Audio System above:
Newer versions (from other companies) could probably house all of your components without any limiting issues.
Like I said. I'm not a fan of mini-ITX builds.
-Wolf sends