Heres.my take as a Ultra Bee owner... The bike is not lacking power. The "Sport" mode is pretty damn good for trails, MX track, etc, enough that I often leave it in "Daily" mode. Sport mode EATS the battery, or lights up the rear tire. If I'm not trying to catch someone I'd rather save the battery to ride longer.
Which is something that wasn't even addressed in the vid. Does the bigger battery get the extra ride time that I want? (Likely so) How much does an extra 20 minutes of ride time cost? My guess is probably $3k ish for just the battery, not including the upgraded controller, let's call that $1.5k more.
So it seems that my money will likely go to suspension upgrades first, while I wait for used batteries or cheaper aftermarket to come online.