``simple_format`` does not preserve the change highlighting (tested in Firefox). For instance
```HTML
<div class="text-diff">
  h1. jljfdsaölksdjfaölkdsjf

dsfkjsaölkjfdölksajf
dsajfölksajfölkdsajf
jfdsölksajfsadlköjf

!yellow.gif!<ins class="diffins">

This is a change</ins>
</div>
```
becomes
```HTML
<div class="text-diff">
  <p>h1. jljfdsaölksdjfaölkdsjf</p>

<p>dsfkjsaölkjfdölksajf
<br>dsajfölksajfölkdsajf
<br>jfdsölksajfsadlköjf</p>

<p>!yellow.gif!<ins class="diffins"></ins></p>

<p>This is a change</p>
</div>
```
which does not highlight ``This is a change`` as changed anymore.