I haven't owned or used either but after using videocameras and my dSLR Canons I'd say go for a real videocamera if you want to do filmmaking. It's less frustrating using a camera made for filming.
The choice also depends upon the glass you have available to attach to the body if you have EF glass then go with the Canon. The Sony does have some benefits so you'd have to take that into consideration. As for 4K the Sony could probably deliver 4K video via time-lapse photography.
In editing, after the fact when you already have your audio, you can try using Audacity which is free. http://youtu.be/ZqeG2ZiN_6A