I am developing a plug-in for Thonny IDE which allows to program micro:bit in MicroPython.
One of the plug-in's key features is that it allows to quickly execute written scripts on micro:bit without flashing.
If user is happy with the result, then the written script can be flashed on micro:bit.
If you are curious and like to try it out then please check out the links below

More info about Thonny IDE: http://thonny.org/
More info about Thonny micro:bit plug-in (installation guide etc): https://bitbucket.org/KauriRaba/thonny-microbit