Although, there are many manual configurations that could be set to optimize individual web pages in sh404, unfortunately, the extension is unable to handle this primary task of SEF URLs effectively. While standard joomla content get translated easily, the extension falters and is inconsistent on popular platforms such as jomsocial and docman in J1.6/1.7. Two of the main extensions that made me purchase sh404.
As noted by earlier reviewers', Joomla has come a long way in SEF/SEO optimization since the humble beginnings of mambo and joomla 1.0. Perhaps, if you are still using LTS J1.5, then you may need sh404, but for websites on J1.6/1.7 this may cause more trouble to you than good. Among others, purged and deleted URLs could resurface when you never expected, raising questions on the database integrity. Today, many new extensions/components contain their own optimized SEF URLS that are short and concise and by far superior to what sh404s algorithm offers.
As and when jomsocial and perhaps docman, with 2.0 coming up updates their own SEF algorithms, sh404 could be redundant.
On support, it is fair at the forums and nothing beyond that. They are quick to blame you as the cause of the under-performing extension and are sometimes clueless on what may be going on, making you wonder if they understand the framework of their own extension themselves.
Frankly, I'm not sure I understand what you're saying. You seem to agree with me on SEF urls being only a smaller part of SEO, but you continue by only talking about SEF urls?
On this topic of SEF urls, then you say sh404SEF is not "consistent" for Docman and JomSocial sef urls? I don't know what that means, especially for Jomsocial, for which sh404SEF has a built-in plugin, extremely "consistent".
We don't have any issue pending for our JomSocial plugin ATM.
Likewise, I'm not sure what evolution between J! 1.5 and J! 1.6/1.7 you are referring to. There has been no evolution at all in that area (routing), and the routing mechanism is one of the few that was not touched going from 1.5 to 1.6/1.7 of Joomla!
Every comment made on Joomla URLs, or more exactly on Joomla routing, is applicable to 1.5, 1.6 and 1.7
The one question you provide more details about: "purged and deleted URLs could resurface when you never expected, raising questions on the database integrity." is easier to answer however: purged url will ALWAYS resurface. That's because sh404SEF does not create urls. It only translates them to a more readable form. It is your Joomla site that creates urls, and then asks sh404sef to translate it. If you purge urls, then next time Joomla wants to display that same url, it will again ask sh404SEF to translate it to a SEF form, and the SEF url will be back. Sh404SEF has no influence on what links and urls are displayed on your site, it only respond to requests from Joomla! itself.
I think you may want to ask those questions on the forum again, and maybe give us a chance to look at your site specifically to provide more detailed answers.
Many others use this extension without problems. I offered my help to this customer to resolve the problems he was having but he would not accept it and instead described in detail how we can do our jobs better.