RodG:
Since you asked.... my opinion of these comments are the same as my opinion of all other similar comments sprouted by the SEO companies. They present a 'lot' of information that looks good in theory, but in practice there is liitle to no evidence to back up their claims.. And of course, of you aren't successful at following their 'tips' they'll happily perform the SEO for you... at a price.....
Those of us that argue against SEO have nothing to gain by doing so, and generally only express our opinions when we get so frustrated at seeing so many people needlessly wasting time and money trying to chase this holy grail.
I started building websites in 1994 - in the days when you wrote the HTML in notepad, and when Webcrawler and Excite were emerging as the first intuitive search engines.
I have followed this subject of "SEO" ever since - and there is so much crap written about it. 99% of what you read on the internet is dubious, and as Rod says, so-called "SEO" companies won't get the ignorant and desperate to part with cash if they did not hype up this topic to the extremes that they do.
The current great driver of "SEO" as a topic, is of course, Google... and everyone wants their site to be "at the top of Google". But at the top for what search terms?
SITE optimisation is more important than Search Engine Optimisation - and if you get the site right, it will rank well. There are TWO fundamental considerations with regard to SITE optimisation:
- TECHNICAL optimisation
- INTELLECTUAL optimisation
The technical relate to just that - making sure that the site operates as efficiently as possible and that it is STRUCTURED to present a flawless User Experience. (Core Zen-cart is 100% "optimised" technically... there is NO NEED to tinker with the way it functions in the desperate hope that adding some "SEO" module will improve it.)
The intellectual side is the "human input" part, and this relates to the on-page content, and the degree to which the site attracts the attention of other sites - including its involvement in popular social media, commetary sites (blogs), news and views sites, forums, and relevant directories.
As Google says itself... build the site for PEOPLE, make it USEFUL TO PEOPLE, and RELEVANT with GOOD QUALITY CONTENT, which operates EFFICIENTLY AND LOGICALLY... and you will feature well in search results.
In short, don't waste time or energy tinkering with code issues. Focus on the INTELLECTUAL side of things.