Mind maps are unstructured, so if your project is unstructured, use it. It is a safe bet to acknowledge the lack of structure altogether than to invent funny names like Inception, Elaboration, Construction to the project stages that do not exist.
The lack of structure brings in a subtle problem. Someone else looking at your mind map will have a hard time reading it. First, because of the lack of the predetermined structure does not allow to grasp the content through the common knowledge of that structure. Second, because mind maps are only half-language, inadvertently using the noun phrases and dropping the predicates and prepositions, together with the grammatical relationships. You may know that the line between "flies" and "arrow" mean "time", but not necessarily your reader.
So, use Mind Maps to acquire new knowledge, but do not pass them onto others.
See Free Mind.
Gantt charts are only practical to track the deadlines and to keep various participants accountable in case of a high parallelization of work. It may look to the newbie that the length of the bars in those charts represents the actual amount of effort, but this is largely false, in reality.
Remember that: Gantt charts are the tool of choice to organize the work of multiple parties at the beginning of a project.