The crossbucks are indeed fragile. Specifically the soldered collar that connect the upright to the 1/8 stereo plug. Seems like they could have either made them more robust or went the other way and used a stiff spring as the collar to give it some forgivness if it gets bumped.
While Fastrack iteslf and the switches are great, the crossbucks are fragile, the lighted bumpers don't light and are quite fragile and the uncoupler sections seem to suffer from sticky activation buttons.
For a system that is meant for play at floor level, the bits and pieces should be up to rough handling and they are not.