Re: How long does it really take?
It's not the years, it's the total hours. People who who train several hours a day six days a week are going to progress MUCH faster than those who go to the dojo a couple of evenings a week. Most of the people training today do not have the financial resources or the will to work at aikido as their full time job so it will take them decades to achieve 'mastery.'
I don't know who may have said 'Aikido works, it is your aikido that doesn't work' first, but I have heard Ikeda Sensei say that many times.