Not exactly an apple to apple comparison. The HF will be a LiFe battery so safer. Factor in the HF 20% discount, the real price is $40, so it's cheaper. Also, for the more battery charging challenged, the HF charger should be idiot proof as compared to the typical hobby charger (cheaper too). The question for me is whether the HF low voltage cutoff is built into the battery pack or the tool? If in the pack, that would be cool. Anyhoo, not many have the guts to run a 20v boat to begin with. Long live 6 volts!
According to the listing, those batteries are Lithium Ions, not LiFe's. There might be some cheaper options on HK, that was just the first one that I came across. Is that humble bragging I hear???
Nah. I'll let the simple, whisper quiet and efficient direct drive brushed propulsion of my boats do my bragging. That's of course if you can hear them over the eggbeater din of all those reduction gears and worn out dog-bones out on the water.
You think your boat it quiet now, just wait till those micro thin props of yours make contact with a hard surface. I guarantee you'll have the quietest boat on the water, but I'm afraid the bragging rights will go to the first lucky Axis captain that realizes you can't move. Gotta go MACHO, man!