According to Steven Gibbs, HDR is *not* designed to take you to your time-line. So even if you physically time travel with HDR allegedly, you're not in your past/future and in an alternate time-line, but supposedly you do *return* to your timeline.
The whole thing is designed to Hyper Dimensionally resonate yourself to a parallel timeline. This says that those who believe in HDR automatically believe in the theory of parallel timelines (I hope I'm right here). Of course other than Gibbs, and a few others we all know about - we don't really have any proof from anyone who's traveled physically. *That* itself is strange because if Gibbs has been selling for 20+ yrs - we ought to have experiences flooding in from people (even if they are bitching how HDR is a toy and Gibbs is a fraudster).
Gibbs said that many people who travel without taking precautions - never make it back to their timeline, which is another reason we never hear back from them.