It is currently (2118, and been like it for a couple of weeks) impossible to edit JS code embedded in Razor files. There is just an endless stream of random Intellisense completion - unless you press escape between pretty much every keystroke.
I really like lots of the new stuff in R#6 (particularly the WPF/XAML improvements - much appreciated), but I have to turn R# off to be able to work on JS+Razor files.
As far as I can tell, all the R# options to do with Intellisense/completion apply across all the languages, so it's not possible for me to disable the JS nonsense without screwing-up everything else. Is that something JB could do, at least until JS intellisense is a bit closer to being usable in the real world?