Well, yamboot. Voith has a philosophy that there is less maintanance with less gearshifts. That's why Voith(DIWA) hasn't gearboxes with more than 4steps. Local or Regional transport. Doesn't matter. There was a time that Voith gearboxes with 2&3steps used. Totally rediculous!!!Less maintanance, MORE FUEL CONSUMPTION&EMISSION! To recognize a Voith gearbox is during brakes. There's a WHEEEEEEEEEEEE sound. Another point is the high engine output. It has to work hard, so more ENGINE maintanance(but that's personal).
Now the ZF-story. ZF(ECOMAT)gearboxes are in use since 1983. Many Bus drivers had to get used to it. More shifts (more shocks). The 4HP's (ZF's with 4steps) had another way to shift. Especially in the first 3. Recognize the loud moanings, but the engines are almost muted. Especially on the 405N of Mercedes-Benz. ZF's shifts till 5- or 6steps. Especially the first 3steps are short. On MAN-buses you can see the steps on the driver's display (ZF 6HP). Well, A Voith or a ZF? I would choose for the last one...
Hope this story is clear enough. Succes.