This is apparently an issue of a corrupted export file (and a possible bug), not a 5.5 vs.5.0 issue. (I re-installed / re-exported with a 5.0 DB and got same results.) Details:
1) WP Migrate DB version: Version 0.5; WP version: 3.8.1; Exported with default options.
2) The exported .sql file begins with css code:
<style type="text/css">
ul .remote-events{
list-style-type: none;
}
.remote-events li{
list-style-type: none;
}
...etc ...
</style>
3) The exported file is truncated at the end, in the middle of "wp_users" (user details changed for safety):
"...
INSERT INTO wp_users VALUES (5, 'jdoe', '$P$BUs23VOZuyoxwFGIQmeCFk45E5dh/', 'jdoe', 'jdoe@mysite.com', '', '2013-02-28 20:49:39', '', 0, 'John Doe') ;
INSERT INTO `wp_us"
4) Did a grep for the css and found it (inline) inside of one of my files: "theme-shortcodes.php". Altho I shouldn't have put the code there, I am not sure why WP Migrate DB would read the contents of this file...
Once I removed the css, the output SQL looked okay and imported correctly.
Sounds like this may be a bug ? ...