i've been using a keywiz for a few weeks now and love it. the way it allows you to program your controls for each individual application your using (emulator/pc game....) and then launch them from the keywiz software is very nice. i didn't understand exactly how useful this was until i installed and used it. it also has a more inputs, a dedicated shift key that doesn't take away an input, and is cheaper than ipac. if you don't care about lighted buttons, imho, it beats it hands down. ymmv tho.
not to say that the ipac isn't solid. it's a proven product, with many satisfied customers. also the cool led output. your not going to go wrong either way.