Finally, a thread that talks about how to sit on the bike.
Like the OP, I have found comfort in sitting properly on the bike and like some others have mentioned, lowering the bars instead of raising them.
What also helped me was moving the saddle back and down and shortening the stem.

What I don't understand is the sitting on the front or anterior of the ischium (Sitz Bones). That is where I get the most discomfort, not only from the tissue at the front of the SB, but it applies pressure to my perineum. When I position my pelvis so that the SB is directly on the saddle with my pelvis in a more vertical position (terminology), I can ride all day with no ass pain and there is a comfortable and natural shock absorbing position to my whole back (lumbar-thoracic-cervical).

Also, the term "flat back" is confusing to me.

I do understand getting flat and when I need to get low or flatten out, I bend forward at the waist keeping the bottom of my SB planted on the saddle rather than rotating my pelvis forward...there may be a slight pelvic rotation...???
There doesn't seem to be an deficit to my ham/glutes engaging or any lower back pain or soreness.

Am I missing something here? Is it terminology?
I enjoy this thread.

The first article that carpediemracing posted was great reading.