You should have a look at QtCreator which follows a minimal IDE philosophy. The only downside is that it's only for C++.
I daily write in Xcode and that is very slimmed-down. In fact, Visual Studio developers typically hate it on first using it because there is only editors on the screen as opposed to property panes both sides of the editor!
And I would say that it is ONLY C++ is truly a benefit to QtCreator!! No use trying to be everything to everyone. Plus, C++ is the best language for everything isn't it? (I jest, I jest)
Unfortunately the only IDE's which seem to support languages I use and work on OS X are java based, and it seems the best option is IDEA or one of it's siblings.