I had the M8 (2019) and totally agree - similar in size/weight. But very very different rides. The fatbob has torque, but the rocket storm just has a lot more of it (and power). The 2019 fatbob felt more nimble than the Dyna and other HDs, but the R3 is more maneuverable.
Meltdowns happen in batteries and humans. Go with antigravity, braille like almost every race team, theyre are no race bikes using lead acid batteries. Go with the pros. The anti gravity 5lb battery has been abused 2 winters, shut itself down last winter, took a week in garage until it accepted charge again. Been in 0 degrees attached to charger and did fine, as long as it stayed charging heat was good. The computer on these batteries does its job, you cant kill it, it cuts off at certain voltage and stabilizes itself for hiw long dont know but for months yes, but computer will see zero but multimeter shows 11.6 i think. 7 years now and has never not cranked because of battery, this is what 900cca looks like. They dont sell mine anymore, theyre like 720cca. Anyway best 500 i spent, they are 200 cheaper now.