Magento causes tons of errors to show up in Moz Analytics crawl diagnostics...tons. I'm not really sure if there is an easy way to fix that in Magento or not, it's just kind of how Magento works.
Your site does have tons of links. Just mousing over your navigation bar shows the sheer number of links on every single page.
Duplicate title tags are also a big issue because of the way that Magento category pages work. These pages have the same title tag, but slightly different content:
http://www.rpamx.co.uk/street/road-gear?color=131
http://www.rpamx.co.uk/street/road-gear?color=127
Magento also has tons of duplicate content issues, also a result of how Magento works. Because most of the page is the same (massive header, sidebar, footer) the pages get flagged as duplicate content, even though the middle of the page (body) might be different.
We ended up deciding to use Magento as purely an online store, and created a marketing wrapper outside Magento for content and structure. It's unfortunate because of how expensive Magento is, but I personally think it will be a good decision in the long run.
Magento's CMS is just terrible by the way...