I'd quite like split-screen editing, that's my main bug-bear, but I've actually structured my use of TextMate around that - I basically just have several Textmate windows open. I've been meaning to switch to Emacs for that, but I suspect that managing buffers (and making sure they end up in the right pane) will take as much effort as dragging a few windows around.
I think you'd be surprised. In my experience I have a fixed set of windows (not os windows, but panes, as you called them), and easily and quickly switch between them with Iswitch-buffers: http://www.emacswiki.org/emacs/IswitchBuffers
this add-on gives you incremental-search to choose among open buffers, and usually it only takes a couple of keystrokes to get the one I want - so instead of moving the mouse around and clicking somewhere small and dragging things around, I am back in business after something like 'C-x b sh' - control-x, b to invoke iswitchb, and 'sh' to get me to my shell buffer...
e.g. in a Django project it'd be common to have users/models.py, events/models.py, polls/models.py - you press Command+T and you can only search on models.py, if you type "pmod" you don't get polls/models.py. Highly annoying when hopping between files is so common.