Over the years Rackspace has proven to be everything I always wanted from my home-based servers, but could never have. Big pipes to the internet and I don't have to worry about power or a flaking hard drive, memory chip, etc, etc.
I'm a cloud server user. The few times I needed support or had a question, the Rackspace folks were always prompt and most helpful. Bottom line is, though, I rarely need support because things just simply run once I put them in motion. And when there have been infrastructure issues that affected one of my servers, I was notified in a timely fashion.
Growth is a major concern of mine too. The new second generation servers and cloud-based load-balancers, DNS and databases let me know that growth will not be an issue at Rackspace.
Over all, moving my systems to Rackspace has proven to be one of the best moves I've made in years.