Has anyone used a front loading (i.e. a seat on the front of a bike) bike seat for a child? My local bike shop says that they are too dangerous (child's legs can get caught in the wheel and weight of the bike will be adversely affected). However, I much prefer the idea of my child being on the front rather than on the back where I can't see him. Anyone got any experience they can share? Any brands to recommend/avoid? Very many thanks.