What are the disadvantages of vBSEO?

A vBSEO is a SEO plugin for vBulletin (click to learn more), that makes raw URLs to search-engine friendly.

For example, when installed, this particular thread's URL would have looked this way:
instead of this way:

Obviously I understand what the potential ("potential" because they are never guaranteed) advantages of using such a plugin. What I want to learn more about are the disadvantages of using this particular product. If it does not work out (or negatively impacts the traffic of the site), I've read some cases when people faced hundreds of thousands of dead links when they uninstalled the app.

One of the disadvantages I've personally noticed (that most people don't think about) is that if you change/edit the title of a particular forum section, it would produce an irreversible effect on thousands of sub-links (thread titles located within that forum), which means they all have to be rebuilt in search engines indexes. This creates almost a lifetime dependency on their product.

In other words, there is a reason why some of largest forums out there do not use the product and I want to know what these reasons are. Also, do the pros clearly outweigh the cons?