I hate that whole 'ten years' thing too... the trouble in the taiji world is that most of those teaching 'martial' taiji are nerds whose most brutal fight had is was usually with their little sister or on Street Fighter so you end up with dubious stuff to say the least. Last night I only taught applications in both the beginner and advanced classes. Once you actually show people how the powerful aligned 'shapes' of taiji fit into head butts, shoulder barges, elbows and cutting strikes you see that it is more or less a brawling art. It can really help to put some spunk into a beginners practice.... from day one.
Also I think the whole 'Chen is this' and 'Yang is that' is a mute point because of the points Prizewriter has already mentioned. We are so far from the source now. Even in my case, my instructor studied directly under Mae Lee Yang, Yang Chen Fu's grand daughter so you could say I'm as close to the source as I'm ever likely to get. BUT to say that I'm studying the original Yang system is stupid, and actually very untaiji. We have no idea of what changes have been made as the system was past down through the generations. And also would you want to study a form that hasn't been improved for 200 years?
Taiji is a dynamic art and one that should improve with each generation - actually each time you practice! We utilize as much sports and medical science theory into our lessons as we do the classics. To deny knowledge is about the most undynamic thing you can do... and not taiji.