Looks like I'm a day late and a dollar short yet again but here goes.
I bought one of those for use afloat with a Macbook. I found it very noisy to such an extent that I had to unplug it to hear virtually any HF at all.
I have replaced it with a Mini-box DCDC-USB http://www.mini-box.com/DCDC-USB
which I have mounted in the enclosure they sell for it. No noise from it at all.
It was a simple matter to adjust the output voltage to the required 16.5 volts using the supplied software running on the VMware Fusion/ Windows side of my Mac.
Only issue was that I had to use the cable from the Hypermac charger to get into the Magsafe socket on the Mac.
I also use a couple of the mini-box 12v-12v power supplies on my Via computer and my LCD screen so as to avoid all the RFI issues that go with using an inverter.
Hope this helps,