I own the mk II and now also a Sony FS100, and to be honest the Sony beats the mk II by a mile. Recording external is the optimal, but not necessary with a camera like the Sony that has two XLRs and proper preamps... the sound actually sounds good, and you can mix it on the go.
The old advice still goes, if you need now buy, if you don't rent when needed.
If I was excited when I got the 5D and made 3 music videos with it, I can't describe how excited I was after having shot the first video with the FS100 (not online yet).
The form factor of the FS100 is inline with the DSLRs and slightly resembles a Hasselblad box. It's modular and not very heavy.
The cheap EF > Nex adapters around made it easy for me to use my canon lenses on the Sony, and I'm looking forward to using my 70-200 for sit down interviews the next month.
You say you travel a lot? I bought the Pelicase 1510. It's specced for cabin sized luggage and the Sony fits right in there including its accessories, and then some.
You can't fit in the still camera as well, but what the heck.
Just saying... take a look at the Vimeo group for FS100. A lot of nice things coming out of this cam.
And again... this is coming from a 5D fan / user (or former...