i dont want to knock these extensions/plugins but joomla is good for seo out of the box if you put the time in. with any of these extensions you'll also have to put the time in so its kind of just duplicating things
i like to use seo ur's that come standard with joomla i.e. /content/view/1819/70/ and then use descriptive titles and descriptions and meta keywords in every page ...
however, like this page says, google love off the page factors. if you put your efforts into this you'll find your rankings are much better ...
its also worth remembering that this guy might not keep his extensions up to date or even if he does there might be a lof of work involved when upgrading your joomla then all the extensions you've installed ...
i guess what i'm saying is joomla is good enough if you use it properly ... in my opinion