Best online app for importing, viewing and editing mpp project files?

What is the best online application for importing Microsoft Project Files (file extension: .mpp)?

To view and then to further edit. A bonus would be able to then export after edits back into .mpp format.

So far I've found Gantter.com and projec.to but would like to hear from someone who's experience of these or others.

From web app dove

• There is GANTTzilla.com.

  Upload & View: Open your Microsoft Project and Planner files right in the web browser!

  Edit: Edit projects using Gantt or PERT views. And yes, we do version control for your documents ;)

  Export: Use converters to quickly export documents into other project formats as well as PDF or PNG.

  Share: Share your project with colleagues and team members or publish the document so the whole world can see it.

  Track: Report, comment and track project progress in Gantt. It's quick, easy and fun!

  From Mehper C. Palavuzlar