I received mine today also and after a couple of similar tests I would've written my own but contacting them is exactly what I planned to do after opening my box,
I have to say after reading their response it does appeal to me to try this product out (in an unused viv for a period of time) and see if their claims are true,
Now that I understand where Hagen are coming from with this design and so far my queries have all flown out the window, however one thing has stuck in my head...
Where the heat mat is now raised, and as you said, leaves a gap underneath for any substrate, feed and bio waste to sit in, surely it would be much more beneficial to (where it is sat off the ground) instead of putting the sticky pads provided possibly add a customised venting system of fine mesh around the base, housed in a sold plastic frame (we're only talking 1cm but in theory it would be beneficial).
This way it's not only being lifted to provide ventilation but it's also covering it's back by stopping that ventilation area being filled... Just a thought.
Couple of pics of the unboxing...
Well wrapped I have to say!
After roughly 5m of bubble wrap I got there! (thankful it was well wrapped, care and attention surrounding their product clearly)
MORE bubble wrap... I have to admit my son will have some fun with all this later!
Just in case people don't know what packaging the substrate heater is in...
And finally the product we're testing, as you can see from the comments above (it's not too clear but it can be made out) the picture on the packaging shows the heat mat sitting on top of the holder, of course they're addressing the issue which is always good to see feedback used! Just a final note on this too, you'll see in the top left a gap between the runners, this will let substrate through easily if it's sand so I'm going to have to fill this with some HA6 before continuing tests (it's going to let out concentrated heat too if I don't, it's only fair), other than that... Tests begin properly.