Several Rackspace cloud servers or virtual hosts at one cloud server?

We use a Rackspace cloud server (2nd generation) for one of ours SaaS applications. And we want to move one more SaaS app to Rackspace as well. Both applications don't have much traffic/load, but they grow up with time insignificantly.

I'm hesitant if to create one more cloud server and to place the second application there, or to install it as one more virtual host at the first server. My main concerns are:

I'm not sure if it'll be convenient to support both developing projects at one server (they're written using the same tools, so quite similar and need a similar environment)
I'm not sure if it's a good idea to set up one more cloud server with the same environment and to spend time on supporting the same servers in parallel (e.g. updates/packages installs). Maybe there're approaches I'm not aware of on how to maintain similar servers in parallel a simple way at Rackspace?

Thank you for your time.

Solution

I have never regretted using separate Rackspace Cloud Server instances for described case. It's very convenient to have decoupled application environments in a long time run.

For easier setup of similar environments it's possible to use templates of Rackspaces's Cloud Orchestration