First of all, thank you for the write up, it´s really good to read this, becuase I haven´t been able to play with the Playtest and I´m intrigued about them.
I´m worried about "Take the Case" because it´s a cool idea, but it´s implementation is weird. It says tipically the subject is a single creature, item or small location. How you determined something was a good subject for the investigation? Did the player switched often in the same scene the topic of the subject?
Also the aplication of the +1 circumstance bonus should be used to "investigate" the subject, not for actions that are not related to the investigation.
Whenever you attempt a check to investigate your subject, you gain a +1 circumstance bonus on the check.
It says typically apply to Perception, Int, Wis or Cha skills. As I understand, you can´t use this bonus to get a +1 to checks not related with geting info about the subject. I understand you aplied it more freely. Do you think it´s better that way? Did the player used the bonus a lot?
The same happens with "Clue In", you can only give the +1 to checks realted to investigate the subject of the case, this limits a lot the kind of checks that other players can do (usually are teh same checks in wich the Investigator is good at).