Is there a drawback to using CEREC for implant crowns? Dentists near me disagree.

Hi:I have personally had problems with cerec crowns and no longer recommend them.  However, I also know some well respected dentist that use cerec and have had no problems.Best,Dr. Maddahi 

Unfortunately, this question, albeit a good one, is too general.  Now that CEREC has choices in crown material, I think it can be a safe choice for an implant crown.  However, this depends on location, bite, and what this crown is opposing.
For example, if someone has a deep bite and/or a grinder/clencher, then certain materials -- CEREC made or not -- should not be used.  Also, we are more concerned about aesthetics in the front of the mouth, or smile line, than in the back.  Finally, is the implant crown opposing a tooth has never been worked on, or has a silver filling in it?  A tooth-colored/resin filling in it?  Another crown?  What is that crown made of?  We want to balance the bite as much as possible when choosing an appropriate crown material to make that it doesn't hurt the guy above/below it.  
As a dentist myself, I would not be opposed to having a CEREC crown placed if I ever needed one, but all these factors would definitely be addressed before I made my final decision.