IMAX Digital vs. Cinemark XD

[UFAlien]

A discussion in the 3D section thread for the new Underworld got me interested in the distinction between these two. Basically, I saw it in IMAX Digital, and another user saw it in Cinemark XD. We got different trailers. Here's what I've figured out, and what I want to know:

IMAX Digital (aka LieMax, Semimax, etc.) is a projection standard for digital movie showings. It involves proprietary DMR (Digital Media Remastering) technology that is said to provide better color than standard digital projectors. They use Texas Instruments DLP projectors in a proprietary configuration as well. Each IMAX Digital screen uses two 2K projectors running simultaneously. The images are overlaid, producing a brighter-than-average image. IMAX claims their image looks better than a single 4K projector, but there is much debate about this. IMAX also uses laser-aligned surround sound in 7.1 format, advertising 12,000 watts. The screen is usually (always?) 28' x 58'.

IMAX 3D is proprietary as well - each projector displays a single eye's image continuously, which is overlaid with the other. Linear polarization is used, so if you tilt your head too much the 3D effect gives way to ghosting and flatness. However, the resulting image is very bright.

IMAX Digital only shows IMAX-approved movies; ones that have been selected for IMAX Digital distribution and been through DMR. This serves as a form of quality control but limits the selection.

On the other hand, Cinemark XD is exclusive to the theatre chain which developed it. Like IMAX Digital, it is a projection standard. It uses a Barco XLM HD30 projector at 2K and 30,000 lumens. There is only one projector, providing potentially less brightness and potentially less detail (?) than IMAX Digital. IMAX does not advertise their lumens ratings for projectors, so a numerical comparison is impossible. The screen size is only described as "wall-to-wall, floor-to-ceiling", with screen sizes "up to" 38' x 70', implying variation.

Cinemark XD advertises "Custom Surround Sound", not laser-aligned or 12,000 watt (though I suppose it could be). No idea what their setup is, 5.1, 6.1, 7.1... who knows.

They use RealD 3D, which is circularly polarized, but since it's only one projector alternating eye view and polarization type at 144hz, it's theoretically darker and possibly less detailed as well.

Cinemark XD can play any digital movie, though, meaning there's much wider content availability - but it hasn't gone through DMR.

So from the sound of it, Cinemark XD is the poor man's ripoff of the poor man's IMAX. Of course, I'd love to find more specifics if anyone had them, such as:

1) Lumens measurements for IMAX Digital projectors
2) Whether each IMAX camera uses a different image in 2D showings to provide additional detail
3) Type and wattage of Cinemark XD surround sound
4) Cinemark XD screen measurements other than the max
5) Whether all IMAX Digital screens are the same size

And if anyone has been to both, I'd love to hear their opinions!