3D and more
It's not just 3D compatibility that's new for 2011. JVC has fundamentally redesigned the D-ILA optical engine on the X3. A new device driver and wire grid mean even less pixel visibility. The result is an astonishingly smooth and cinematic image, with astounding black levels.
Also new this year is the provision of Adobe RGB, DCI and sRGB colour profiles, expanding the projector's appeal beyond mere Blu-ray playback. Gamers and digital photographers take note.
Despite an obvious long-term commitment to 3D, both with its projectors and, increasingly, its camcorder lines, the provision of a separate 3D sync emitter (PK-EM1) strikes me as a little short term. Unlike Sony, which has built the sync transmitter into the lens barrel of its own 3D projector (the VPL-VW90ES), JVC has elected to keep the unit separate, meaning you'll need to hardwire it directly to the rear of the projector yet somehow accommodate it within your install.
The reason given is that 3D is being sold as an optional extra in most sales territories. However, JVC UK has elected to include the transmitter and a pair of glasses as standard.
The projector supports frame sequential 3D Blu-ray, Side-by-Side 3D as used by Sky and other broadcasters, plus other formats you'll probably never need. Googlers should be aware that the X3 has a sibling model from JVC's Pro division, the DLA-RS40.
Outside of the nomenclature there's no difference in the product. Similarly, the DLA-RS50 and DLA-RS60 correspond to the DLA-X7 and DLA-X9 respectively.