Cool idea, saw vids from Interbike on that.
I've been a convert of the wooden walking bike, the one with no pedals. It was originally the Like a bike and the imitated all over the place.http://www.youtube.com/watch?v=DNf-seURC7U
Both my kids learned on that bike and NEVER had to rely on training wheels. Training wheels are a very bad concept because it doesn't focus on balance. After my daughter rode this for about a year, we put her on the 10" diameter wheeled bike w/ no training wheels. After about 10 yards, she was able to pedal and ride w/ no help. She was barely 5 yrs old at the time. Then my son took over the bike when he was about 2.5. He was able to ride a 2 wheeler at the age of 3.5. He's 4.5 now and has ridden that 10" two wheeler around our neighborhood, including 6.5 mile family ride last week.