I have three sources of data. Firebug can measure download time letting you view for yourself the download speed in your browser on your network connection. The Google Sitemaps service also records page download times and reports a graph in the crawl statistics section. Finally the http://mon.itor.us service can report page download times as well.
Historically I've observed these average download times: VPS server from Rimuhosting 1-1.5 secs, Dreamhost account 2.5+ secs, Advanced account at pair.com 3 secs (or more). That is for Drupal websites, the sites which have static HTML pages download much faster at around 1/4 sec. Those numbers are from the Sitemaps crawl statistics.
The performance is good except when it's bad.
This graph is for the same website from Google Sitemaps crawl statistics. Note in mid-January that the line dropped downward than before. That lines up perfectly with the move of that website over to A2 Hosting. And of course that the line is lower means less time to download pages and a website that feels faster.
That's good enough to be very attractive and I almost am sold on their service. But.. I came across a couple usability issues with their service (specifically their VPS setup is very obtusely confusing). Meaning I'm still looking.