I have just finished reading through your thread with great interest....we have 2 ES's, a 5 year old female and a 2 y/o male. They have been great additions to our place and although the male can still act like a court jester once in awhile they are all business when it comes to anything stepping foot on their property or flying overhead. I have found they are incredibly intelligent and are prone to observe and calculate to handle some situations, the male definitely took longer to mature, I think our female was born a mature worrier!
I have had a lot of success with using simple key phrases or words to focus their attention, especially with the male. I repeat the phrase 'watch it' when something was out of the ordinary, the female didn't need it, but by repeating it when the female was onto something allowed me to get the same reaction/attention from the male even when the female wasn't present, another phrase used is 'where is it'.
They are great varmit dogs and have eliminated any incursions from the neighbors garbage dump also.
My mother also has a male (half brother to my female, same age) on her farm and he really came into his own around 16-18 months, he is a dark sable like your boy and is truly an impressive dog which can take on about anything in our area except bear.
I believe you will find your time and effort will be well rewarded with this breed.