so I have already installed one on my M9...it went rather smooth. so today I decided I have it so , I went to install on my 92FS Brigadier..  I have no idea what is different about this slide compared to the M9, but installing was easy..the issue was with function. it had no where near the same spring tension  as my other install on the M9, and no matter what I tried it would stay in the "safety" detent position... you can actually feel the detent engage the area.  I took it apart and put it back together about 25 times over the past two hours... I even polished the part of the slide the detent rides against... it would still lock into the "safety" postion and I would manually have to disengage it.  
   my first kit just seemed like the spring had way more tension and it would pull itself out of Safety and back into Fire.  I gave up on it and put the original safety back in for now... I'll send Beretta a E-mail and see if I can get another spring...if that is even the issue.

I had the same issue with my Brigadier.  The slide is too wide.  I installed it on my old 92F instead.  I'm hoping when they reengineer the kit to be one sided that it will work better.

I kept trying because when I would get it together it would work.... then I would put the roll pin in to connect the two halves and it would not... maybe the right side was out enough to allow the spring to work freely, by putting the roll pin in it would draw the right side in to align the hole... making it too tight.  I agree the slide wall thickness is probably the culprit... and it's my fault for not thinking ahead.