Yes if you want sharper images. The HDSI is 2" longer, has longer SI crystals that produce a thinner SI pulse which creates sharper images.
PM sent with more detail.
_________________________
Humminbird Helix 12 CHIRP SI, 1198c SI, 1198c SI, ONIX 10 SI NT, Helix 7 CHIRP SI GPS G2, SOLIX 12 SI, 360, RC-1