Hi Terri !!
The TRD temperament feel like not stable is because we always plan to changing them for adopt our human standard
The TRD are not an aggressive breed but do carried aggression, there are not a problem if owner recognized and knowing how to deal with !!
The TRD personality could change all the time depend on how owner raised them!
For example : when a lonely TRD pup who live alone during day time which owner going for work will soon develop into a well independence thinker and will ignore recall once he got fully mature and busy on own business, so it's his fault ? or because he is untrainable ? or the owner faults ?