I have Berners and they are a very sensitive breed who often do not accept the gentle leader. I second the endorsement for the sensation/sensible harness. Same function as the gentle leader, with front body control, but the clip is on the chest. My excitable Berner girl wears the sensible harness and it is highly effective for controlling her excitement around dogs - a common Berner trait.
Finding a good positive trainer is the key who can help work with you on teaching emotional control. The mouthing will come to improve as well - he is still a baby - with consistent reinforcement. Remember that Berners are slow to mature and must learn good bite inhibition. My girl took a lot longer than my boy did so they are all different. Because my girl lacked emotional control (excitable, mouthy etc.) she had a strong need to use her mouth and exercise her energy through her mouth. To remedy this, we always provide her with something to bite down on - quickly hand her a toy or the leash when entering etc. It is key to provide him with the appropriate outlets while reinforcing what is inappropriate. She would still love to grab my arm and at first, always bruised me - but through patient reinforcement in teaching the word "gentle" - she learned to stop. So teaching a cue-word to release any pressure like "gentle" and re-directing his energy onto something appropriate - a toy is key.
To learn more about the breed and discuss with knowledgeable owners, join the Berner list at http://pets.groups.yahoo.com/group/Berner-l/
Thankyou for the link will take a look later.
We are having some success with the dogmatic now a kind of halti it doesn't ride up the eyes as the others do,we still have our stubborn days but ignoring him seems to be the key.
The mouthing is improving we do direct him onto something else sometimes he gets so excitable and jumps at you and grabs your arm or hand but a firm SIT!! seems to do the trick he then stops.Met someone the other day with a Berner and he was saying one of his previous dogs didn't stop mouthing till he was a year old.
Once we have overcome that he will be a great dog,he is only 8 months old and is doing really well and we have to remember he is still a baby hard when he weighs so much though.