Although I'm a huge fan of Egg Beaters, while reading your question I didn't see any reason for you to switch. How are the Shimano pedals not satisfying your needs?

One of the biggest reasons people go from Shimmis to Egg Beaters (or Times) are issues with getting your cleat in and out of the pedal in muddy conditions. Shimano pedals are prone to gumming up. The Egg Beaters and Times (and Frogs I'm told, but I think they're a knee surgery waiting to happen) clear mud much better.

The other major reason people switch to Egg Beaters is that they are the lightest pedals out there (though I could care less as I ride Mallets).

If you're riding in the desert and you're not concerned about weight, your Shimano pedals are fine. Furthermore, the MXR is not an "upgrade". It's Crank Brothers' cheapo pedal that is not serviceable. The Chromes are the minimum of what you should be looking at to "upgrade".

http://www.performancebike.com/shop/...cm_cat=1069410
http://www.blueskycycling.com/view_product.php?pid=19
http://www.bestwebbuys.com/bikes/sea...=i-srch-search