I discovered internxt quite some time ago before I found it on appsumo and I was positively delighted by how it worked as I used sia for quite some time, which I did not like. Internxt worked different, its quicker and seems more reliable.
I have tried files ranging from 1gb to 10gb and all worked. The 10gb file took over night to be up on internxt while dropbox would take 2-3 hours.
Send with internxt is one of my favorite features since it lets me basically share files with folks all over the world and I can even limit the number of times a link stays available at one time.

I'd love to see improvements in the overall speed, but other than that, Internxt is awesome. I love the app, the web app, and the Mac folder.