Here is just a tip from an insider.........I can't tell ya who......there is no difference between 60m and 90m dds tapes except for a microscopic thickness. the whole idea behind the hype was to sell more tape! and it worked for many years. There was even hype about the difference between DDS tape and Dats made for music. The claim was the formulations were different, this is false also. Actually DDS tapes are better because they are made in sterile conditions because of them being used mostly for DATA tape backup drives( the concern here was dust), ones for music are not. I have always used sony 90m DDS tapes and have never had a problem as a result of the tape. Normal wear and tear yes but it had nothing to do with the tape. Nothing against the Oades, I have the utmost respect for them, but people will believe what they want, I just have trust in what I was told.