Acorn4 will know from his 120-bass endeavours whether he needs the diminished column. If so, go for the 72-bass.

He will also probably know whether he plays with guitarists in E, hardly an obscure key, for example 'Early Morning Rain' first two chords E major then G-sharp minor. With only twelve rows, that is an eight row jump and you will miss it as often as land it. On an 80-bass, with the overlap, it is only a four row jump.

The choice is yours.