The best linear motion is the one with the most rigidity, repeatability and longevity. In CNC plasma and Routing applications cheap motion like bearings on steel and wheels on steel rod are not enough. You need to ask more from any mfg that uses these methods openly without ways of scraping, lubing or protecting the rail system.
The industrial standard is one set by years and years of trial and error and eventually engineered efficiency. The hardened profile linear rail is the most used rail in metal manufacturing from CNC Laser, machine tool to accurate robotics. The Star Lab CNC system uses true hardened and ground profile linear rails with scrapers and wipers.
5 years, 10 years or 20 years down the line true linear rail survives the test of time. The motion of mechanical structure only requires very minimal support initially. The eventuality of minimal support will get sloppy when you need it to repeat. We put the hard work in design, efficiency and longevity without cheap gimmicks of motion on every machine.