I know the question on what the best Rails host has been asked and discussed before, but I'm looking more for advice with my specific scenario.
I have a SyncML server that requires a minimum of 512MB RAM that I want to hook up to a Ruby on Rails front end. I'm going to be using a Linux environment to serve these. What I'm putting together now is just a prototype so I don't require high bandwidth or too much storage, but scalability is important because I don't want to have to search for a hosting provider later.
I've currently got the SyncML server set up on a Godaddy VPS, but to host the Rails app I heard its best to do it somewhere else. Would it be a good idea to just keep the VPS and use something like Google App Engine, or Heroku for the RoR app and connect the two? I personally don't think its a good idea to have things on different networks. The RoR app needs to talk to a MySQL server, which in turn speaks to the SyncML server.
What is the best way to go about this right now (Shared/VPS)? Which hosting provider do you recommend?
I don't mind having to setup the machine for RoR myself, although if its ready its always better.
I've been looking at Slicehost, Rackspace Cloud, RailsPlayground, HostingRails, and Site5.
UPDATE:
Thanks to your responses I've removed Site5 from the list of contenders, but I actually found another company called Serveraxis. Anyone heard of them, are they any good? Can't find reviews...
UPDATE 2:
Is Cloud hosting good for something like this, in early stages of development? I don't require a lot of bandwidth, my only requirement is that 512mb of RAM for the SyncML server.