To me a tool is an extension of one's mind or body that goes into all projects that you work on. I can give away an application or a library. I can't give away a tool, or at least, it wouldn't really make sense to. I want to use all my tools to build a project, all my projects to use the same tools. That's why I stick to Ruby rather than bouncing around. I use Coffeescript/jQuery on web projects but I consider it a kludge, though not as much of a kludge as using Opal would be. I'd want Ruby integrated tightly into the browser before I'd prefer it over Javascript. I don't mind Coffeescript because I find that if you stick to a certain convention, Coffeescript is as easy to maintain as Javascript and I prefer the terser syntax.
My ultimate goal would be to be able to hack on all my tools like I hack applications. For example, I'd love to be able to replace Sublime Text with redcar, an editor written in Ruby, I've taken baby steps in that direction with my git scripts. I haven't decided if it would be better to write my own editor though. I'm probably at least a few years from that being able to integrate that into my workflow.
This approach gives the advantage of ceding ultimate control back to the programmer, at the cost of some internal inconsistency.