I use a lot of SS flareless tube fittings at work. We normally use Swagelock, there is still some Hoke floating around and a little bit of Parker. I personally prefer Swagelock, plus the ferrules and coupling nuts are interchangeable with Hoke Gyrolock fittings.
After they were torqued onto the tube, I have seen Swagelock fittings hold a few hundred pounds of pressure without leaking when they were only hand tightened. Once they are tightened all the way, correctly, I have never seen one leak. And we use them in some applications over 3000lbs.