Ctrl+R SPACE seems like it's a bit iffy for some cases, especially since I use Ctrl+R so frequently for history searches. Using it instinctively (like I use Ctrl+W) wreaks all kinds of havoc; if I do something like Ctrl+R python to get a previously run command, then hit Ctrl+R SPACE, then it moves to the previous commandline that contains python instead of staying where I am and moving back a word. Still, something to explore -- I can probably find a way to use this.