You'll have to deal with all those concepts regardless of language, so it really doesn't matter. Java, for example, uses all of those concepts in popular frameworks (Spring, Play, Hibernate) and it's quite a different language than Ruby. Lots of people make noise about language and frameworks, but software development is really about abstractions and concepts. If you know, roughly speaking, what an ORM needs to do, then it's not too much work to pick up another one if you need to switch to another. Understanding the concepts is key - the implementations are just window dressing.