Wind and maneuverability would be my concerns. Taking the LF kit necessarily involves a separate piece of luggage/method to carry it, whereas the 6x6 will travel "lighter." Also you can use the 6x6 in walking around mode, and you cannot do that with the LF rig.

I've traveled with a 4x5 and came to the conclusion that I wouldn't do it again Unless it was a once-in-a-lifetime location where photography would be (basically)the only reason I was there. I don't do many of those trips! Most of my trips are for business (not enough time for photography) or they are family vacations and my kids don't want to stand around when I set up for 15 mins to take 1 photo! I am traveling in a few weeks and I'll be bringing a 6x6 TLR to wander around the streets and parks with. It won't require anything extra besides a light meter; maybe a light knapsack or fanny pack in case I want to tuck it away and be less conspicuous.

Enjoy your trip. I recently learned that it's easier to get to Iceland than it is someplaces in the United States, from the east coast of the US!