Hi LDH. I'm a "newbie" here, but I have been lurking for several weeks. I have enjoyed many of your posts. They make me think hard!
As far as "heart", the Society teaches that it is the "inner person" or the "inner motivating force of your life". They don't totally ignore the "heart", but mostly what I had learned from the WTS about the "heart" relates to the ministry they ask of their adherents. Do you do "half-hearted" service (with your attentions divided), or are you perhaps "double-hearted" (leading a double life)?
As far as "conscience", what they say about "Bible-trained conscience" and what they expect of their members are logically 2 different things, in accord with what you point out. My example (I keep harping on this in my posts, because it is what currently is most sensitive to me) is the shunning arrangement. Nothing in the Bible supports the current extent of the JW shunning policy. If JW's followed a Bible-trained conscience, they would not shun family members who have erred or who have been accused of such. Recently, I have met up with 2 old friends who say their JW families have dropped the harsh shunning of their DF'd family member.
As far as people flooding out of the truth if they would listen to their doubts, I don't know. Sometimes their social "strings" are so tight that many or most would feel compelled to stay, figuring that the "good" outweighs the "bad". For me, it's only after I was shoved out on my own that I was able to let the doubts I had harbored since a young age become actual, logical thoughts. I'm relieved to be out!
Thanks for listening!