Actually, bushings are more reliable, and that's why the jet engines in F16's, FA18's, F22's etc all use bushings, called slipper bearings, and the shaft and bushings in your turbo are operationally and metallurgically identical. The only part to lubricate is the shaft at the bushing points. Each bushing has journals through which the oil is force-pumped onto the shaft, which spins in a thin film of pressurized oil. In addition, the internal cavity is under a high-pressure oil shower. Bearings, on the other hand, have to ride in milled-out 'races'....too many pockets for oil to pool, coagulate and eventually coke. The fact that the ball bearings may be ceramic is meaningless if the oil coagulates in the races. Though it combines the advantages of the LPT (faster spooling) and the HPT (higher top end speed) this kind of turbo is primarily for competition and has to be torn out and rebuilt frequently, unless there is a sophisticated after-run cooling system installed. But even then, they don't last anywhere near as long as the Mitsubishi turbos in our Volvos. For long, dependable turbo life, you want what the FA18s have: bushings.

The number one cause of turbo failure is NOT the bushings...it's sclerosis of the oil return outlet (drain) at the bottom of the turbo. If oil isn't changed frequently enough, and it's composition isn't such that it can withstand the heat, coked oil begins to form on the lip of the tube. Eventually, this will choke off the drain entirely, reducing flow to the shaft bushings. The back oil seal then blows out, resulting in tailpipe smoke when the turbo spools up...but even then, the bushings will likely be OK.

Many of us prefer synthetic oil because it is far more tolerant of extreme heat. It will flow happily at temperatures that cause lesser oils to break down and varnish hot surfaces. Under extended load and at full spool, your turbo can reach temperatures as high as 1400 degrees F. That's hot enough to break down oil, but not hot enough to melt iron....and far, far too low to affect the shaft and bushings.
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(98 S70 T5SE misc mods, mostly lighting) (92 940GLE)