We are very aware of the path problem in certain domain-model scenarios and try to mitigate the problematic query creation by substituting it with cascading (data-driven) matches.
Please also understand that the query might seems "insane" but this is exactly what we can derive from the metadata provided by the annotation in the domain model. Loading the N3PMVOrder will follow all reachable relationships by your definition. When SDN detects that there will be a circle because of the relationship definition in the domain-model, it can (in the current release version) only fallback into the path mode becaue it does not know where/when to break the infinite loop.
As I said, we are working hard on fixing this problem and our feeling it that it seems to work AND improve the situation a lot. As a reference model we also created a scenario where the DB will run OOM and now it just takes less than one second to load all data.