This whole concept of raid 1 in a separate location is nothing new, its whats severs are often used for after all.
So the issue is really one of compactness. The ICY DOCK certainty is compact, but that comes at the price of having to have a separate power brick supply which means having to power off at the plug in point!
It also would not be as flexible as a server setup, (such as more then 2 drives) but that may not an issue if you know you will only ever want a simple setup.
Many people have achieved the same arrangement by simply turning an old PC into a host server and installing RAID, but of course that wouldn't be as portable as The ICY DOCK.

Only you know what you want out of a RAID 1. If being able to very quickly change drives* whilst being portable is high on your agenda then this seems a good solution.
(*I didn't see any mention of the units ability to rebuild a failed drive, so whether its does it the same way/speed as a sever? perhaps should be looked into if thats your intent)

Just comments...cheers