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,
73
Frank
VK3JFH
VP8DNM