It isn't whether tubes, these or those, it is more about the implementation of the tubes. Price doesn't guarantee performance. But, considering your question, it would be good to know the truth for the sale of a used product. Instead, there are often catch phrases used to set you at ease of buying someone else's equipment. Often times I will see-- "upgrading to new equipment", "I have too much equipment", "wife says sell", and my favorite, "going in a new direction." I certainly am not saying these are all tales to lead you on, but, is that the real reason for the sale?
Lastly, when buying new or used, is there the option of return if you hate it? I wish that I had thought that through before wasting time and money. The power of impulse buying (even impulse from the past, "I have always wanted one of these) is great. Ok, now I'm done. Good luck.