I'll add my .02. I got these for Christmas to replace an outdated set of tower speakers, and they are fabulous. The sound is powerful, with great bass, and excellent surround capabilities.
While it's true there are limited inputs, I use an optical switchbox to go allow me to use four optical inputs for the speakers. I can go from my Xbox, PS2, Gamecube, and a PC... all with a flick of a switch. And the switch is an inexpensive device from Radio Shack that works well.
As for RCA cables... that's incorrect. While there is some included wire with the system, you can use any wire you like with these speakers. They have gold-plated screw down connectors on the back, and I use 18-gauge wire with mine to help prevent interference and hum. It works well, and I've had no problems with my setup. I simply put the Z-680 speakers where my others had been, and connected the cables. Then I pulled the cables out of my receiver, and hooked them all up to the back of the subwoofer. And haven't had a single problem.
This setup is now all I use, and I couldn't be more impressed. It's saving me a TON of floorspace and shelf space, and allows be BETTER sound than my old speakers... at a fraction of the price to seperate components, etc.
I got mine for Christmas... since Amazon had marked them down to $200 with free shipping. Seems Mom and Dad missed that deal, and ended up paying about $240 when shipping was extra through another business on Amazon's site. But they are incredible, and I'm so glad they got them for me.
The only negative is the remote, which isn't near as stylish as the speakers, and the range and angle to get it to work are aweful. But that's a minor gripe for such great sound and reasonable price. Either set of Logitech's would be awesome, and I'd recommend whichever is cheapest.