Over the years, Google Analytics has improved in terms of how it reports traffic which is 301 redirected from organic SERPs. That said, increased data isn't necessarily accurate data especially when unlike Urchin, 301 redirects aren't recognized by Google Analytics or visible in the dashboard.
Experiment: To determine if organic traffic entering via 301 is attributed properly by keyword and intended landing page URL in Google Analytics.
Hypothesis: Organic traffic entering via 301 redirect is not attributed properly by Google Analytics.
Background: SEO focuses on optimizing specific URLs, for specific keywords and content pages based on user intent and SERPs. Marketers have come to rely on Google Analytics metrics for insights about website traffic and marketing effectiveness but seem unaware of how organic reporting accuracy is impacted by 301 redirects.
Procedure: Create a page at one URL and allow Google to index that page in SERPs. Redirect the first URL to another page which contains different content. Observe both Google Analytics and Google SERPs for each of these URLs over the course of a week.
Result: A week later Google Analytics reports that the second URL ranks for terms which it does not rank in SERPs. The second URL isn't indexed by Google SERPs but, Google Analytics reflects organic traffic by keyword, URL and shows a bounce rate for the second URL.
Conclusion: While still a best practice, 301 redirects pollute Google Analytics data and hamper the ability to glean organic insight about intent.