As a long time SauceLabs customer I just tried Sauce and I am loving it!

Being able to open multiple browsers at the same time is fantastic. I can launch them at once and take a look at them. We have been using browserstack but constantly closing and opening different browsers is a lot of work. Screenshot: https://dl.dropbox.com/u/132641/screenshots/sauce.png

It also seems to be faster compare to browser based solutions.