I don't think the base country will make too much difference. The biggest issues I had (that would not have occurred in the US) were with cultural barriers.
No matter the country, language can mostly be addressed with the right process and managers, but the attention and service that US customers expect is not something culturally that exists in many other places.
Getting that right, so that my team leads and PMs meet customer expectations was the hard part. I think that is where many offshore projects fail.
If your team is committed to delivering quality, and you, as the end client know how to communicate your needs and check the deliverables, things usually progress very well.
If your offshore team doesn't understand or care about this (many just don't get it, because customer service is NOT a thing in most countries outside of North America and Western Europe) then you will have frustration no matter where you go.
My clients are about 75% US based and I would be happy to talk with you directly if you have more questions or want to discuss a project. Reach out to me here: ethan [at] abovebits [dotcom]