Google Search Engine Algorithm Update - Website Traffic Visitors Results Down

We have noticed a sharpe drop in website visitors since Google actioned their late September search engine update.  We are hoping that the situation settles down and our printer cartridges websites becomes more visible again.
Fortunately we have many existing customers who continue to visit our website, however it is always necessary to continue to add and replace those who may not return again.  The latest Google algorithm change has halved the traffic to our main website.
We have been told by our SEO friends not to panic and to hold tight for the situation to resolve itself.  It can be worrying however when half of the existing traffic is diverted elsewhere overnight.  For younger more unstable companies this must be a concerning time for them.  When much of their hard work seems to have been wasted.
Reading various blogs and pages regarding these issues one finds different reasons for changes in site traffic.  One of them is the use of descriptive domain names; in our case printer cartridges.  Several people have written that Google are penalising these domains in search results.  However talking to search engine experts this theory bears little fruit.  Some websites with descriptive domain names are still featuring high up on natural searches.
More to the point, the general consensus of opinion seems to be that Google is now more interested in active content.  Websites that change their online content often should be ranked higher.  Of course modifying content takes time which gives an immediate advantage to larger organisations with greater resources.  Companies who can afford to employ a permanent person assigned to these duties will benefit the most, meaning larger organisations will prosper with  these latest changes.
All of the above said, the jury is still out with regards to the new inner workings and mechanics of Google search.  We will all have to wait for the dust to settle; but hopefully the situation will before clearer soon before too many sales are lost!