When our swcah daughter , now 11 yrs old, was about 4-5 yrs old we moved from CA to VA.  So of course we had to change endos.  When we did, and they did the initial lab testing/exams, we came to the realization that there really isnt an absolute in the endo community when it comes to treating and interpreting care for a cah child.  Her labs had pretty much been ok but the new endo thought she was being undertreated based on his knowledge and we raised her meds.  Then we moved to Tx and the endo there thought she was being undertreated and raised her meds again.  Then when we had to make the decision on who was going to do her second surgery we decided to go to Cornell in NYC and while there be under the care of Dr. New and her staff.  There they did all the genetic testing and of course testing on our daughter and she decided she was being way oversuppressed so we lowered her meds.  So you see, different endo drs have different opinions of the same tests.  I think its great to get a second opinion and your endo should understand that it is your child and you want the best care.  I doubt it will even bother him.  Follow your heart.