After a season of playing with these two units, I have to say I'm very pleased with both. The issue of phone battery life can be addressed with the portable chargers.
the vex sonarphone is more sensitive, portable and user friendly than the HB fishin buddy. However there is sometimes a glitch in the wifi and I have to reset it (pull it out of water and let it shut off) but otherwise very good at marking my rattle spoons and tungsten jigs, seeing every jig stroke and any lookers coming up. Playing with the gain levels is important from hole to hole to clear clutter enough but still see the jig. The thickness of the ice determines how deep into the water column it takes before "surface clutter" clears enough to allow you to see the signals.
The HB fishin buddy has a very good battery life, at least with energizer lithium batteries. It has no problem seeing jigs and spoons, marks fish at depths no problem. On cold days there is more blurring on the screen as far as seeing small jig strokes, and display will run slower. The ice has been too thick to use the side Finder feature so I can't coment on that yet. The transducer is 24" long, but the ice thickness hasn't effected signal image enough to be noticeable.
