There're agile maturity models out there, believe it or not. Even the growth to higher levels of agility have to be modeled. And even the stages towards mature agility are predetermined, which is strange because there's no limit to agility.
The more models, the more business... Every model brings the opportunity for external meddling, for external intrusion into your organisation. External authorities are empowered to judge your progress or maturity alongside the adapted model. It's about time to withdraw power from external authorities who are judging your level of agility and to be your own authority. That will say if your organisation is mature or not. And along with withdrawing power from external authorities come ownership and responsibility. But also authenticity and originality and more space for joyful expression, when reaching higher agility levels.
The level of agility is not measured by the extent of adapted agile methods, but is measured by your own standards. Agility is in essence not something to be objectified and to be judged by an outsider. Only the inside can determine the level of agility on a deeper level. A certain level of maturity is needed, though. Although that doesn't mean the organisation should adapt another model in order to determine its maturity. Adapting another model will not be the way to go when aiming to thrive as organisation.
Consider the following example: a dancer has an idea in mind of the movement to be expressed and has the intention to express that idea. When the dancer doubts or rethinks in every moment its next movement, the dance won't be smooth, nor agile. The whole dance would be rather the opposite. When the dancer fully lets the idea flow into manifestation of the expressed dance, without any disturbances or blockages, the dance will be observed as smooth and agile. Intention and action are more seamless than in the former example.
The major determinator of agile maturity is the extent of delay between the intention to manifest an idea and the actual manifestation of that idea.
Have you ever seen a flock of swallows (those little birds) not being agile? I don't think much discussion, debate and reconsideration takes part in the collective of the flock, nor in the individual of that flock. No, rather the opposite: in one seamless motion the whole moves according to the dream or idea they have in mind. There doesn't seem any delay between the intention to manifest the movement and the actual movement - very mature! Too bad they aren't complying to any maturity model...
Maybe they aren't so agile after all.