[Freesurfer] Question About Longitudinal TRACULA Analysis

Dear all, I wanted to ask you a question about longitudinal TRACULA analysis. I'm analyzing a group of patients with different time points. In my configuration file, I used "affine registration from the individual T1 to the MNI T1 template with FLIRT and a correlation ratio cost" as the inter-subject registration method (set interreg = 1). However, I’m considering whether it might be better for my analysis to use "nonlinear registration from the individual FA map to a custom FA template with symmetric normalization from ANTs" (set interreg = 5). I would appreciate your thoughts on this. Thank you in advance. Best regards, Sara