I like the Customer Adoption Spectrum because it specifically points to adoption of different customer types. Who is your product currently suited to, who would you like to get, and what do you need to get them, how do you speak to them, etc. etc.<p>It also fits well with the Crossing the Chasm model where you can look at each customer segment and measure adoption.<p>However, I don't think throwing away the "Product Market Fit" term is necessary, as it is still an apt description, but just don't get stuck thinking that Product Market Fit happens only once for a company, it happens for each market you target.