I suggest for any researcher looking to do their project abroad, to take a soft approach. Don't assume you know the answers to someone else's problems. Don't assume you understand the field site from only reading reports and papers. Don't really assume anything - come with an open mind - educate yourself on the issue, yes, but not too much that you form hard and solid opinions. Try to stay open and let the people where you are going teach you something. It is one thing to study in the classroom for your degree, it is quite another to learn in the classroom of the world. There are no grades, no rating system aside from the friends you make, the colleagues and networks you develop, and the impression you leave behind. As much as you are learning from people you meet, they are learning from you too - and not necessarily what you say, but what you do.
A researcher exploring a system outside their own culture may have its drawbacks - misunderstanding of social norms, ethnic histories, identity, and cultural practices - but the advantage is that the outside researcher has fresh eyes not already tinted by all this cultural baggage. The outside researcher has the potential to look objectively at a system. So is the value on objective or subjective or objective with context...? I think the value is on all of these things together. One must be able to grasp the objective realities of a system - say a river system: such as the hydrology, climate, precipitation, topography, terrestrial biology, aquatic biology, geology - PLUS the objective with context: borders, population density, infrastructure, and economic uses PLUS the subjective: why people do what they do - that is where history, culture, identity, and things like this come in.
Essentially research is learning more about how people think, how other systems function. And if you are lucky, you prove yourself wrong time and again and blow your mind of assumptions. The researcher abroad can bring added benefit by knowledge from another system - the scientist may have worked on another river and recognizes something important about the new river of interest that is related. These comparison skills put the systems we study into a global context. The researcher abroad can bring an added benefit of outside knowledge, but needs to have inside cooperation in order to understand more the big picture and the details. The foreign researcher's domestic partner (not in the usual sense of the term) is invaluable.
I remember a lecturer at my university challenging me with a question at the end of my initial presentation of intended research in Ethiopia. Her question was why I was going to Ethiopia, why not stay in the USA to look at our own complex issues surrounding international rivers. The answer can be simple - my research is considering current dam construction - grand scale possible changes to rivers - and in the US we don't have any large scale dam projects being developed. We are dismantling them. But if I consider the question really, it is interesting why I was asked. There is a value to having someone from outside of the cultural, political, economic, environmental, and social systems consider changes, consider projects, consider challenges. The value is in the exchange. Not only the exchange that the foreign researcher brings to a field site and people they meet, but moreso the exchange that the researcher abroad takes away from the experience. The researcher learns to see with new eyes. This can help to reshape how that individual approaches their own domestic issues and questions and research interests. Also, the communication can allow these new ideas, from the domestic researchers, to reach a wider audience through the foreign researcher's resulting work - publications, lectures, presentations, etc.
All in all, I think that going out to a different country to examine a research question, investigate the problem in detail, and present the results to their academic community and hopefully a wider audience later, requires more than just a casual observation and objective involvement. It involves connection with that place through the people - and free exchanges with an open mind - new ideas could change everything. Great things are possible in this world when we share.