Beating around the bush
I don’t like the Medieval Merchant-style production. It is too rich and lacks trade-offs for when to increase presence (explore) versus when to get resources.
New rules. Mostly cleanup and clarifications suggested by Matt Worden, but also a few changes:
- 
Shell routes cost more to explore. If shells are more valuable than fish they should be harder to get
 - 
Bids on routes must start out matching the route type but can be later mixed fish and shells
 - 
Kula Gifts track renamed to Kitoum Track. The name is of course inaccurate as Kitoum may be transferred in Real Life
 - 
Kitoum received for deliveries to markets of size 5
 - 
Game ending clarified for the deadlock case
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Island scoring changed to Kardinal und Konig-style area majority
 - 
Tie breakers for end-game scoring changed to shells then kitoum.
 - 
Added third place scoring
 
I may still retreat to the simpler 5/3/1 scoring for islands. The only real difference is that ties and majorities are more interesting with the current rules.