AS OF MAY 2016, THIS PLUGIN IS NOT BEING MAINTAINED AND WILL NOT RECEIVE ANY FUTURE UPDATES. 
CONTACT ME IF YOU’D LIKE TO LIST AN ALTERNATIVE HERE.
Shows word and sentence counts plus a readability analysis of the post 
currently being edited using three different readability measurements.
Readability analysis is an attempt to show how difficult a text is to read. 
There are several methods of doing readability analysis. The most popular 
methods are used here. The Flesch and Flesch-Kincaid methods use formulas based 
on the average number of words per sentence and the average number of syllables 
per word. The Gunning-Fog method uses a formula based on the average number of 
words per sentence and the percentage of “hard” words (words with 3 or more 
syllables) in the passage.
Both the Gunning-Fog and the Flesch-Kincaid give a score that is the number of 
years of education the reader must have completed to understand the text. 
Different types of writing calls for different scores. Technical subjects may 
require a higher level of education so a higher Fog or Kincaid score is 
acceptable. Informal writing may try for a score in the 7-10 range. The Flesch 
score is a percentage. The higher the value, the better the readability.

FD Word Statistics Plugin

Shows word and sentence counts plus a readability analysis of the post currently being edited using three different readability measurements.

Alley

Matthew Boynes

WordPress has a wonderful editing model with its “draft workflow”, where writers can save unpublished drafts, preview posts, submit drafts for review from a superior, and even schedule a post’s publication. This is all that most writers and teams ever needed for a blog. WordPress has extended beyond blogs, and has grown to be the preferred platform for any person or team writing for the web. While WordPress has evolved, its editing model has not, and this editing model is limited. Once a post is published, edits cannot follow the same workflow. That’s where this plugin comes in. This plugin has two powerful features, the ability to clone posts and the ability to replace posts with another, which combined, allow writers to leverage core’s “draft workflow” for published posts.
<h4>Features</h4>
<ul>
<li>Create clones of existing posts. The replicas are created as drafts, and have all the same data (including terms and post meta) as the original post. The only things not cloned are child posts (which include revisions, attachments, and other posts)</li>
<li>Replace one post with another. The replaced post becomes a revision of itself, the replacing post is essentially deleted, and you’re left with the replacing post’s data with the post ID and slug of the replaced post.</li>
</ul>
Combined, these features give writers a pseudo-“fork and merge” model. Published posts can be cloned, the clones edited as any other draft can be, then the originals replaced with the clones.
Individually, these features are equally as useful. You don’t need to use the “fork and merge” model to take advantage of this plugin.

Clone & Replace

Gives you the ability to clone posts, and replace posts. Together, you have a very powerful tool for a fork/merge editing model.

FD Word Statistics Plugin vs Clone & Replace