Many thanks for the new SNAP release! I had a look at the extended speckle filter set. Looks like you dropped the threshold in Refined Lee altogether (i.e. no distinction between either non-calibrated or calibrated intensity).
Do you have a reference to the source of the IDAN filter? Looks interesting, but have not seen it before.
The IDAN has been adapted from the polarimetric case and generalized for single pol.
G. Vasile, E. Trouve, J.S. Lee and V. Buzuloiu, "Intensity-Driven
Adaptive-Neighborhood Technique for Polarimetric and Interferometric SAR
Parameters Estimation", IEEE Transaction on Geoscience and Remote
Sensing, Vol. 44, No. 6, June 2006.