I just had an Idea, and I cant believe I didnt think about it before. If this idea has already been posted in this monster of a thread, then I apologize, because I cant read every possible page lol
Instead of nuking modes or changing "effectiveness" of modes (one of my original ideas), why not just lock the community goal into the mode you first picked it up in? If you pickup the community goal in open, you can only contribute in open. If you pick it up in group/solo - then you can only contribute in group or solo. Any bounties/trades/etc turned in in a different mode will have absolutely no affect on your standing.
Although, they would have to have a way to make sure the person doesnt buy the trade in open, log into solo, go to CG station, Log back into open to make the trade. Im sure they could come up with a way to "tag" the client each time you login to a mode, and if that "tag" changed since you bought the goods then the trade (or kill) wont count.
Everyone still affects the goal in the same way 100%, everyone can still participate, there will be no advantages or disadvantages but at least one of the bigger problems being discussed will get resolved
I know this wont silence the people who want to try and do "blockades" and the like, but at least it will silence the people who are complaining about "Community Goal Mode Switchers"