NEX 6? Any downsides?

Mirrorless lenses are all more expensive than SLR lenses right now.  This is economic: there's not yet enough competition in this segment to drive prices down (or decades of secondhand lenses out in the market), and the system is still so young you're paying for Sony's R&D costs.  Sigma are the only third party that have gone in with competitive offerings to date (and with optical designs that were made for their Foveon sensor which is why they're so fabulous), but when Tokina, Tamron, and Samyang roll out their lenses it's going to be a lot more interesting for the budget photogs.