Hi Eugene! This is a good question. To be honest, I'm not 100% sure what would happen in that situation, but I can tell you that we have lots of customers doing big business using the plugin, and we haven't encountered any issues. In other words, we have quite a lot of stores -- both large and small -- using the plugin, and no one has said that it has negatively impacted their SEO.
As for the specific impact of the IP Redirect on Page Rankings, Google's Algorithm, crawling etc., I'm not 100% sure of the technicalities. But anecdotally I can tell you that so far we haven't exerienced any issues with using the plugin.
Hope that helps, just let me know if you have any further questions.
Thanks,
Tristan.