I love this question. I had been thinking about it as well. I decided to dive deep into our data and see what we could find.
We analyzed over 55,000 Facebook (product)
Posts from the month of September 2013. For each page, we looked at the average when they posted via Facebook vs posting via Instagram. When compiling the data, we look at the median of all of the page’s averages. To maintain relativity, metrics were divided by fans at the time of the post.
Our initial hypothesis was that using Instagram (company)
would cause a small bump in engagement and exposure. The logic was two-fold: Facebook may have increased the weight of the objects, and posts from Instagram are always photos or videos—with visual filters—that are potentially more eye-catching.
However, our data shows that metrics such as Engagement, Organic Reach, and Viral Reach all remain fairly consistent while not using Instagram.
Median Engagement per Fan was fairly close, 2.39% for Facebook vs 2.15% on Instagram. This difference is within normal expectations.
While Organic Reach had a small decrease (within normal expectations) from 12.51% to 10.90%. It should be mentioned again, this small decrease is most likely due to a simple variance, as opposed to a finding.
This difference is a little bit more significant than the difference in Engagement. For us, this data illustrates that the two are roughly even between the posting APIs. Viral Reach experienced a small, modest decrease (again, within normal expectations) from 1.47% to 1.31%.
Examining this data has shown that using Instagram seems to have little to no impact attracting engagement, or on a Page’s distribution in the news feed.
As we examined the data, we formed another hypothesis. Do the pages that use Instagram inherently do better than pages that don’t use Instagram? To clarify—does their attitude towards trying new platforms reflect in success? To keep this answer a reasonable length, I'll link to the rest of our analysis: How Does Posting Via Instagram Impact Engagement on Facebook?See question on Quora