I currently use KeyClone, but I've tried both. KeyClone is so cheap the price doesn't factor in for me. I use KeyClone for these reasons:

a. Works with Vista. Neither I nor a friend of mine have been able to get Octupus not to crash on start up. I guess you've had better luck.

b. Octupus has no support for round robin which is a must have if you are multiboxing Shamans.

c. Can't specify process affinity in Octupus. I use multi core machines and each runs multiple copies of wow. Doing this by hand is painful.

One great thing about Octupus is that it seems to always pass the correct keys. I use '1' for Lightning Bolt and 'Ctrl+1' for nova totem. When using KeyClone sometimes I will press '1' to activate Lightning Bolt and instead I drop a bunch of totems. This has caused me a few wipes. To "fix" it, I have to press the 'Ctrl' key a few times to get it unstuck.

I don't have the latest version of Visual Studio so I put an order for it a few days ago. Once it arrives I'm going to modify Octupus and add the features I need and debug it under Vista to see why it is crashing.