With so much discussion about how to make putting reflect Ball Golf difficulty or interest it takes my mind to the most putting strokes within 40' I've ever had:
The Hippodrome. 4 Courses full of pucker putting.
Yes, it's Gimmicky in many places. But I think what the designer is going for is similar to what you are all asking for in regards to putting challenge and risk-reward. You can be sure that after playing all 4 courses, your mindset and scorecard will be different than most anywhere else you'll play.
Anyone played it? What did you think?