The HDS sounders are great.
I have HDS 5m gps and a HDS 5 x sounder, but if doing it again I would not get a hds5x because they do not have an SD card slot, so are problematic to do software updates etc, I would get a hds5 combo unit instead. That would also give you some redundancy of you keep the Garmin gps as well.
Cheers
ML