Would be interesting is to see the conditions of learning. Tower or no tower, wake boat or i/o, and small person vs larger person.
I myself learned behind an i/o to wakeboard with no tower, but my first wake to wake was behind a Malibu with tower and wedge. Ever since that day I could also wake to wake behind the I/O also. I am 6'4" 230lbs and it took me awhile to wake to wake.