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Yes it will definitely help as it will give some credibility - especially with newbies and businesses not very online savvy. Don't expect to learn and remember a lot from those tests....most of the learning will come from actual experience aka trial-and-error, online tutorials/blogs, forums & your peers.

Do you think it could be something to do with the panda update? My clients are based in the US and Canada so I am not up-to-date on the Panda rollout status in Europe. Hopefully others can offer feedback on that topic.

The Panda Bear is such a complicated beast, it's hard to narrow down what the problem could be without thoroughly looking at your sites. We had a similar problem on a previous update and had to try many different things to sort the problem, ultimately I think it was a combination of things on our sites that happened to trigger one of Panda's algorithms into dropping our ranking. It's probably worth bearing in mind that sites do sometimes disappear from G when updates take place. It's happened to us before and within a couple of weeks the site came back to where it was. I'd suggest trying to improve your sites in this time though, so that when your site is next crawled, G can see that you're starting to make improvements. One of the main things that seems to affect panda is duplicate content on your sites, so if you've got various pages with the same or similar content then I would suggest using the canonical tag to sort them out. Looking at your sites quickly, I've noticed that; Some sites (e.g. Wannapack) have a high number of inbound links from relatively small amount of domains. This could sometimes suggest a link scheme. The link profile on some of your sites contains a lot of 'spammy' directories and article sites. It may be worth trying to get some higher quality links from genuine sites, perhaps packaging review sites or how to sites. It may be worth getting rid of some old content and putting some new high quality content on your sites. Panda can often downgrade a site just for having one or two 'poor quality' pages. Try and limit the amount of duplicate content you are using across your sites. After all G can see they're sitting on the same server and may look at this in a negative way. Try looking at the page below for tips on link building with Panda; http://www.blueglass.com/blog/link-building-in-a-pandas-world/ I'm sure there's people on here who could direct you better than me on this topic, but as a starter I hope this helps!