I think alot of your question will be answered by what your planter is....CCS or box?  1.5 bu or 3?  Here, we are conventionally tilled -everything from moldboard plow, deep rip, to one pass FC and plant.  Our planter is at JD 1760 box planter with 3 bu hoppers.  I was surprised by the amount of the DF requirements changed by the changing of the amount of seed in the boxes.  You might run from no hydraulic down force  full in moldboard plough COC ground with full hoppers- up to 125# by the time you are empty.  And when doing endrows, it seemed as a general rule - regardless of what your were running for DF pressure in the field - you can about double it on the endrows.   This seemed very consistent across all our tillage conditions.  

Also with the spring type downforce, we would have trouble "trenching" with the row cleaners with full hoppers, but by the time the seed got about empty in the hoppers, it would be acceptable.  This year, the problem mysteriously disappeared, and those Yetter pin-type row cleaners that I have learned to hate with a passion - actually worked decent because they were kept at the right level by the DF system and weren't either trenching or just along for the ride.  It appears that with our factory spring system, we were likely way over applying DF with full hoppers - while trying to maintain depth in more stable soils with empty boxes.

We upgraded our AL 2 channel system this year to the  AL ISOBUS 6 channel  so two rows together.  While the CANBUS system was ok, the ISOBUS system is the cat's meow. The only thing missing is the ability to map the data - coming next year I am told.  The system is more invaluable than I would have ever believed. 

Good luck