I just finished reading the Then vs. now differences thread in the TKD sub-forum, and it made me wonder how people would treat younger instructors with more experience than them. I'm going to use myself as an example for this. With overlap, I have around 23 years of experience, without considering overlap, it's over 30 years experience. However, I'm only 25 years old myself. How many of you would be willing to accept a 25 year old instructor, who had 20 years experience in an art you have no experience in? Alternatively, how many of you would accept a 50 year old instructor in the same art, who had 10-15 years experience in the art. From my personal experience, the answer in reality tends to be that more adults (over 30 or so) will rather learn from the 50 year old with less experience than the 25 year old with more experience. But those same people are fine with their kids learning from the 25 year old, as long as he isn't the "head instructor". If you were to start a new style, which would you rather learn from, and why?
Personally, I need to separate this into two, if not more, distinct questions.
Would I be willing to accept a 25 year old as an instructor, and would I be able to give that 25 year old the same level of respect I would to a 50 year old instructor? The short answer is "yes." The longer answer is that I generally approach people with an open mind and a listening ear. If the potential instructor is able to show mastery over their subject matter, explain concepts effectively, demonstrate techniques appropriately, and answer questions and make corrections patiently, then their age isn't necessarily a factor. I trained briefly under a couple of instructors that were much younger than I am, one a female just a couple of years older than my daughter. I had no problem with this, because they were clearly dedicated to their art and were knowledgeable, competent instructors.
Would I be able to respect an instructor of 25 with a claimed 23 to 30 years of experience. Bearing the above answer in mind, and respectfully, I wouldn't be able to seriously accept the claimed time in training. You didn't start training at two, and certainly not before you were born. I understand that you are likely saying you have X amount of time in one art, and X amount of time in another, and cumulatively that equals Y amount of time total. I tend to look at it from the perspective of "what age did you begin training." It was at this age you began developing skills as a martial artist, learning and understanding techniques and the principals behind them. As an analogy, I took three years of History to earn my minor, four years of political science to earn my major, along with two years of astronomy, two years of English Lit, etc... I don't tell people I have eleven-plus years of undergraduate work. I earned a four year degree.
Going one step further, I do agree with others that the younger a student is, the less likely they are to examine techniques from a critical perspective. That tends to be, in my experience, something that develops later in one's development, sometimes not until well into adulthood. That isn't to say a 25 year old can't be better at critical analysis of an art, it's theory and techniques than a 50 year old, not even a 50 year old with more time in training. That is determined by the individuals themselves, and their desire and ability to think critically. Which takes me back to my first response.