Very nice review; I am surprised that it has not been upvoted more
(perhaps because, as you point out, there's not much demand by the userbase for tar functionality in Perl).
Your post could well be considered a template for quality review posts here at PM.
Here's why:

-you explained why the module could be useful
-you gave us a good idea of what the features of the module are
-you gave us example code using the module
-you listed weaknesses of and potential pitfalls in using the module
-you gave us information about the tar file format that would be useful on any platform
-you finished with a nice summation of the applicability of this module

I learned a lot here...thanks.

Scott