Good post. I agree that the emissions perspective is pretty complex. The top two importers Japan and South Korea would probably just use less nuclear if LNG went down in price. And that's almost half of current LNG imports accounted for.
Alternatively natural gas plants are tanking throughout Europe right now, while coal is doing pretty well. The European Emissions Trading Scheme appears to be a dead dog, so the only short to medium term prospect to improve the situation for gas, and weaken it for coal, in Europe may be to decrease the gas price. So, US LNG exports may lower EU emissions. Having said that some EU governments aren't that happy to pay extra for renewables or nuclear, so lowering gas plants may hurt renewables/nuclear as much as they hurt coal.
But if I was to lay my hat somewhere it would be that LNG exports will increase emissions. All you need to do is look at the top importers (page 11 here): Japan, Korea, UK, Spain, China, India, Taiwan, France.
Clearly Japan & Korea will see increased emissions if gas prices go down. The UK is similar, with the current Chancellor wanting the UK to push heavily on gas, and new coal is not on the table anyway. Spain's electricity grid is a complete mess right now, and cheap gas will just kill new renewables. It may have marginal benefits for India/China, but not many. Taiwan is considering whether to build new nuclear, so cheap gas is a negative there. France is a dead end for coal, so cheap gas can only be bad.
May be other factors that I am ignoring, but the climate benefits of LNG exports seem questionable.