I have never seen that kind of turner before, looks like it works in much the same manner though. Just turning the eggs side to side instead of end to end, but still at a few degrees at a time. If it tried to roll them too far I'm thinking it would require the eggs get too much momentum in order to get over and that could be a problem if they went rolling into each other, all over the bator, etc.
Just a thought, low humidity can be the reason for chicks to get stuck in their shells, but inadequate turning can also result in poor development that makes them unable to get out. There was a study done with goose eggs in France, I think it was, wherein they found that end-to-end turning of 180 degrees, rather than side-to-side turning resulted in better hatches. And I wonder how applicable that is to chicken eggs.
We do tend to see those that hand-turn having more hatch problems than those with end-to-end auto-turners. But then, hand turners are also opening their bators several times daily which makes for another very big variable in the hatch methods. So, I guess, in short what I'm saying is that I'll be interested to see what results you have with this turner since it's turning side to side, rather than end to end and at the same time, removing the open-bator variable.
Of course we could also -- and pretty accurately, I would wager -- theorize that the several times daily opening of the bator, rather than the method of turning, is a big enough variable it would be causing the low hatch rates in and of itself. Opening the bator reduces humidity, temperature; reaching in and moving eggs is a major environmental disturbance, etc. etc.
And just another thing to think about, I also have found with my own hatches that "late hatchers" -- those that hatch at day 21, rather than a bit early -- tend to be more likely, regardless of humidity in the bator, to become "stuck" in the shell. My theory is that these chicks are less vigorous, non-thrivers so to speak. And it is what it is, nature-wise. There is never more than one per hatch, so it is acceptable to me. But, theoretically, if one were having a number of non-hatchers in each batch and was also noticing hatches on day 21 or after the two may be related. We know that slightly hotter bators can contribute to quicker hatches -- just by a half a degree or so -- and so, it seems, it might be an interesting variable to play with as well. If you could "force" the chicks to be thrivers via forcing an earlier hatch with the temperature...
Fun things to experiment with if nothing else. Here's hoping for a good hatch for you, regardless.