Axure’s worth in responsive design

I'm just wondering on the wider audience views on how worthy using prototype tool Axure is when designing a responsive site.

I have project where the deliverable is a responsive site. However, I'm just wondering whether the site design should be tackled using Axure to prototype the site in the first place. Or go from sketchy and the UX & front end dev teams working very closely and collaboratively.

My reservation in using Axure first (or any prototyping tool) is that you can make the content, layout and structure do whatever you want. However using HTML markup there would certain constraints and considerations. These issues cannot be wholly captured in a prototyping tool but would be in HTML mark up.

Obviously there's some more pros and cons, I would just like to hear what you fellow UXer's have to say on the subject.