The solution to consistency for putting seems to be a cylindrical putter lopakagolf.com
Wouldn't changes in that putters elevation off the ground change the effective (negative) loft .......something that a flat face doesn't do. It'd be an interesting thing to goof around with.. I believe Yoda had a negative loft putter once upon a time , not sure if it was flat faced or not or what his conclusions were.
A few things to consider in all of this: Homer was a pool player and his putting mat was a well worn , nearly bald carpet remnant.
BTW Homer's opinion was that consistent putting came with a consistent Hinge Action (any of them but there were implications of course) . He believed that once a Hinge Action was mastered you didn't really need to practice putting as much . That one day wonders and inconsistency gave way to the easy fine tuning of path and Hinge Action.
Im still waiting for that day to arrive personally ....
used the cylindrical putter today with great success, the greens are questionable but this putter puts a roll on the ball that just TRACKS right through pitch marks and deviations. I seem to be able to play less break and make a shorter stroke. I will never go back to a lofted putter...