Just received my creative katana last night, here's my quick impression compared to my X7+XM7 setup previously
1) Katana definitely takes up alot less space, but it takes in the way of my keyboard cable. So have to buy an angled usb cable that I can loop around the katana instead of under it.
2) Sound quality wise, the X7 combo definitely sounds better. However, it's a distinctly 2-channel while the Katana is able to imitate surround sound better.
3) I need to find a better placement for the sub because at it's current position under the table, I'm not hearing any bass
4) The rainbow led effect under the Katana is very nice
If you use your PC more for gaming and watching movies, and have limited desk space, go for the Katana.
If you're a stickler for sound quality and listen to alot of music, go for the X7 combo.