My current host is gatorhost.com. They use Ruby 1.85 and rails 2.3.2
I use Ruby 1.9.1 and rails 2.3.2.
Will I have a problem with any of my rails environment apps if I use them on my hosted domain?
Murphy's Law sez: yes.
If it were me, I'd set up a VM with the same configuration as the host you're deploying to and at least pre-deploy to it and *run your tests*.
Then, if it fails in production, you know what new tests to write. 
FWIW,
Good idea - thanks mate