That Truma is a nice looking unit. I would be curious to see how it compares in quietness.
We have the Australian Houghton AC. Advanced RV introduced it for their vans about 4 years ago. I think they were the only distributor at the time and were putting them in for other vans and selling to other manufacturers. I don't know if they have that exclusivity now.
It is as they say 3 times quieter and 20% more efficient than I assume Dometic. You can definitely tell the difference and carry on a conversation. Though we have it, we have yet to use it in over 18,700 miles of travel in two years. That said, we in the past didn't use our past Dometic's either. We needed our Dometic once and found it didn't work, probably from no use in four years. We now do test the Houghton on just about every trip.
This is their 4 year old video on YouTube. If you can't find it just search Advanced RV on YouTube. However, I can see it here:
Ours is forward on the roof where Mercedes Benz installs their AC units on passenger vans and not in the back where the bed usually goes in Class B's.