I can do editing in the code while looking on previous results, also I can read the code with my eyes while waiting for results to finish. I caught several improvement places while just looking on the split screen while waiting :)
sometimes it takes too much time ti give any meaningful response and you are clueless what is going on.
give it a try and show to junior developers, they will love it
RubyMine is good for proof of concept (at least I used it in this way). I didn't have a chance to create production grade project yet.
Other team used different approaches to ruby development and I heard that after trying so many tools they finally end up purchasing license for RubyMine as it's easy to integrate with versioning system and there is very few issues in the team collaboration flows.
I like that many people already use this IDE and you can easily find help on the industry specific forums or just on the stack over flow.
Glad to see developers of the product taking time releasing new versions often in the response to customer feedback and early bug reports.
I think product can be used in many situation and feet different needs of the typical software company or organization with significant software presence in their business model.
Each team is different, so I can only share opinions that I observed in our company and not sure if there are serious problems on really huge projects.