I have used Jetbrain's PhpStorm at work and I really like it. With regards to PHP I think PhpStormi is by far the best, even more so when it comes to debugging.
If RubyMine is similar then it will be awesome and I strongly recommend it. Jetbrains also offers fully functional trial versions, so there is no risk.
If it weren't for a bloody bug in Sun's JRE, I'd use it more often.