Just thought I'd check my memory usage right now, don't have much open (often there will also be Unity + Maya + Mudbox open) but right now I'm at 14.4 GB.
I'm not saying the Pyra needs anywhere need that much, but on every Windows computer I have ever owned, having 'too much' RAM has never been an issue. My current box has 32 GB in, and I'm often using over 16 GB (but less than 32 GB) so I seem to have about the right amount for my current usage.
Edit: in the above you can see: computer browser windows, chrome, skype, notepad++, command terminal, Tortoise HG, emClient (email), Visual Studio 2012, Photoshop, Eclipse, Calculator, Postbox (email archive), task manager and mspaint (the last two for making this screenshot).