Okay - I see there's many different views on this topic here.
I think I'll close it off (from my side) with what I learned from talking to the guy developing the contraption I referred to in the beginning.
Besides for his dad (which I believe is not a good reference due to being his dad) he had two written references that had done around 500kg honey both and basically said that it will indeed help on getting the same amount in every jar and also saves a bit of time since one can get jars, label, cap etc. while the system takes care of the rest. And none had experienced any "accidents" with the system.
I know there are multiple approaches to filling, some more manual and some more professional (and expensive) and that I could do with the manual approach.
But I think I'll try it out - since it's relatively low cost, I like the approach he has taken and he convinced me that it actually works.