Having tried both styles, the Piccolo is a much more stable design, with the rack attachment mechanism vs. the seatpost mount for the Trek. For a 3-year old the gears may be a distraction, but for an older kid, they're definitely useful. We have the single-gear version of the Piccolo (Kazoo) and now that my son is 7, I wish we had gears. In addition to the Kazoo, we also have a FollowMe tandem that we use with a geared 20" bike. With the Kazoo, he ends up not being much help at higher speeds, but when we use the FollowMe tandem with his bike, he is able to switch to a higher gear and really push us along.