alot of people run titleless bike as track bikes and i haven't heard of any problems, i ran one but only for two events but never had an issue... i have heard rumors that one time cops were checking vins for stolen bikes, but its probably something that happened one time for a good reason and got turned into a track day urban legend because i've never actually talked to someone that has actually seen it happen, just people that know people that heard it happened to their friend at a track day

but do it, you won't regret it