Had the chance to listen to the Creative X7/X7 LE and the EMU XM7 and here's my mini-impressions. Location was IT show, so it's definately not ideal listening conditions.
First off, EMU XM7 runs significantly better on X7 LE over standard X7. There's more meat on the bone(better dynamics, punch, slam, sharper transients) with LE. As Audiophile/Head-fier, I highly recommend taking the white LE version over the standard black version if you intend to pair with EMU XM7.
The difference lies in beefier power adapter on the LE. It can be bought separately as an upgrade to the standard X7.