I have the UHK, I really like it (it is so far the best keyboard I've used). I could make use of another row of keys, but they chose to minimize size, which makes the keyboard nicely portable (especially if you put the two halves together back-to-back).
A big part of the appeal of the UHK is the agent, which lets you configure the keyboard any way you want. Not all keyboards let you do this, so it's often an apples to oranges comparison.