Obviously most of the time these types of units aren't going to be a problem, but you do have to realize that when you add one of these gyros, stabilizers, autopilots, powerboxes, etc., you're adding a single point of failure into the critical path. Personally I care not to do that on my jets, but if you do, you need to realize what you are doing and make sure you are confident in the unit (i.e., its been *thoroughly* wrung out).
On the Hobby King side, I do buy a lot of their stuff - but the failure rate of their electronics is way to high to use them in a jet - IMHO.
I do sort of agree with essyou35 - although he may have stated it a bit more harshly than I would have.
Bob