The decoder issues that Ron correctly detailed are independent of the issues with the sprung trucks.
[rant]
No vested interest in Kato or FVM here. I love my Kato GE units and prefer them over FVM's, but I'm fully prepared to prefer the FVM ACe's over Kato's. Kato made some dubious design decisions with the ACe's (and the new version of the 70M). 25% of my ACe's have trucks that fall out when you breathe on them, and they cannot easily be repaired without new parts. This is pretty bad for a company whose engineering is usually top notch. The tilting side-frame issue is minor but annoying, and completely unnecessary. In theory, the sprung design is supposed to increase pulling power, but my Kato GE's pull better than my Kato ACe's.
[/rant]