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Country IP it has a small importance, I would maintain the script on a US server if your audience is from US/com.
I wish IP address didn't matter so much, it would be nice and convenient, not to mention cheaper, to simply use one host.
I'm surprised some people don't think the IP location makes a difference.
It didn't back in the day, but as Google ramped up their local search and improved on local results I'm pretty sure the server location became a factor weighting the results.
I would have thought the move would be problematic for rankings. Very good to hear it went without trouble!