Sublime Text 2 + GoSublime has been a really great experience for me.
I am using the evaluation version of pycharm and I must say it is quite impressive, although paying for an editor does seem odd after using emacs for so many years but it is a well designed software and I think worth the price.
That said I have been asked to give sublime text a try and I must say it looks a lot better than pycharm, I think will give it a try next (it is certainly a lot cheaper and if I understand correctly has much wider language support than pycharm).
I think for experienced devs, a text editor is quicker for dynamic languages (less experienced people will get good mileage from an IDE). Go is sort of weird in that it reads like a dynamic language, so a text editor is Good Enough, while the static compiler helps to catch the sort of bugs that float up when you're doing manual (and hence, human-error-prone) refactoring work, like changing the type of something, which IDEs tend to automate for you before compile time. That's why GoSublime really is all you need for Go, as far as I can tell. (NOTE: I've not written anything like even a medium project in Go).
It hits the sweet spot between emacs and pycharm quite nicely and I am at this point inclined to buy a license, I think an IDE is more useful for languages like java or scala but for python sublime text will do for me.
Re. the use cases for an IDE, my point was that as my side projects keep growing in size, I need something which is smart about things like refactoring, comprehensive autocomplete, support for debugging etc.