As with a lot of things, the tools make the job. Sometimes a "cheap" tool will be just fine while other times (like tubing flaring, bending, etc) the tool makes the job.
I've got the "cheap" flare tool, although it is a Snap-On and works half ways decent. At work, the shop has one similar to the Eastwood unit to do both double and bubble flares in SAE or metric tubing. As you said, perfect flare every time. Good thing too, being in the so called "salt belt" we go through brake line like it's going out of style.
You do know when you will make the most perfect flare you've ever made in your life don't you? It's the one that you forgot to put the tubing nut on the line first. Not that I know that from personal experience, whistle, whistle, whistle.