There are definitely advantages to have everything on one easy to access single page. But what are the implications of using this style of presentation?
So what are the advantages of a single page?
The statistics do show a generally larger conversion rate, in non-lingo this means more people are making contact as a result of visiting the website. It also provides a way of presenting your offering in one easy to access page, providing of course it hasn't been designed so that the user has to scroll through a lot of stuff they aren't interested in to get to where they want. Good navigation can resolve this.
Google will match search phrases in similar in your content, but context here is important. So careful use of h2 text or sub heads is needed to define the sections of your page. Normally you would use the main heading or H1 text to define the relevance of the page. But as Google generally only expects to see one of these on a page.
If you have a story to tell the the single 'scrollie' page is great. This leads the user through your story and builds the image you want to set in the user's mind.
Why should I avoid the single page?
The first thing is it severly limits the opportunites for key searches. This is fine if you have a very well defined target group. Most of us don't have that. So the contrast with a multi-page website is all those opportunites it presents to target different searches and target groups. It also has limitations if you have a more complex offering. There is a practical limit to just how much you can put on a single page.
Google likes to see an active website. One that has new or changed content on a regular basis. It does not favour static websites that once built never change. The easiest way to tackle this is via a blog, news pages or such. Somehow a blog just isn't going to work on the single pager.
Making it work
In reality it really does need to be an either or. There is clear evidence that the single page format does get results. But you don't have to limit yourself to the one page. The solution I believe is to have the home page in the style of a single pager. Offer a brief introduction to the various aspects your offering but with the added opportunity to explore more about any particular part. This would go to a separate page to discuss further. Then you can add the extra content such as news or blogs or information that is relevant only to a particular group. Two birds, one stone comes to mind.
Cavespider, giving it some thought.