We're considering a switch to RoR (from CakePHP oddly enough) at my job, but this gem dependency nightmare gives me pause. I ran across rvm in my research, and it's supposed to solve these concerns. I'm wondering if you have used rvm and whether or not rvm solves the problems you've run into in the past.
In short, no. I've used it, but I think that the problems that RVM solves are largely orthogonal to those.
I don't use (or need) RVM on servers, and I don't use it on a daily basis, but I find it useful for testing gems across multiple interpreters before I release them.
Thanks!