I don't believe the above review is entirely fair because of a misunderstanding with the how the device charges when hooked up to a computer. When hooked up to a Mac, the iPads are trickle charged. When not hooked up to a computer, they charge at full rate.
That being said, this device is vital for large deployments. If you use this and Configurator, you can update iOS on 20 devices at a time in about 10 minutes total. You can hook up another PowerSync D20 to the second USB port and update 40 devices at a time. This is simply the fastest way possible.
Imaging - I can restore approximately 20 iPads in about 40 minutes depending on the number of apps that need to be put on.
I'm an iOS developer and have a sizable collection of iOS devices that I need to keep charged at all times for development testing. I've been shopping for several months looking for the best solution to keep my iPad devices charged while connected to my Mac. After a fair bit of looking, I decided upon the PowerSync D20 because it looked to provide the charging capabilities I needed with the connectivity to my Mac.
Unfortunately, it only delivers one half of that capability at a time. While connected to a Mac, the D20 goes into a 'lower power mode', which is code for: 'it does not charge iPad'. None of their documentation points out this fact in an easy-to-understand way, expecting potential buyers to deduce what 'lower power mode' really implies. This was a pretty significant drawback, because I not only wanted to be able to charge my iPad devices, but also be able to sync them at the same time.
While I was mulling if I could live with this serious set-back, I suddenly began to hear a very loud noise emanating from the D20. It turns out that the device does not rely on passive cooling to bleed off excessive heat, but will turn on a very loud fan to cool it off. This was the last straw on this camel's back and I knew that the D20 wasn't quite the device I was looking for.
The connectivity issue is understandable, I just wish they were more forthright about it--especially for how pricy the device is--but the loud fan was an absolute deal breaker. One of the major selling points (for me, at least) of using Apple products is that they are very quiet compared to their PC counterparts and the D20 was ruining that aesthetic.
For my day job I work in a research lab and we have many, many iPad devices needed to keep charge, but not necessarily sync. The D20 would be very appropriate for that environment, except for the noise issue. I'd really hate to be in the same room as the D20 and twenty iPads as it makes more noise than a lot of the servers I deal with.
Bottom line: Product falls short on explaining its limitations and for as much as the D20 costs, it should be better engineered so as to not require active cooling, or at least have a more robust fan system that is not so rough on the ears.