So it *sounds* to me like you should be fine getting 14 miles out of a 36v 72ah pack. I know you have an aftermarket controller so just know that going faster reduces efficiency at an incredible rate and kills range. My guess is that the butter zone for efficiency is in the 15 to 17mph range.
I do not know of anyone who has tried EB yet.
Supposedly RoyPow has a great price point but I've been unable to find someplace online advertising the price of the RoyPow S3880 pack.
I see
https://bigbattery.com/products/36v-...o4-116ah-5kwh/ is 116ah for $399 more than EB and it includes the charger also, same issue where I have no reputational info on them. But at 116ah it is 62% more capacity than the 72ah battery you mentioned. I am not recommending this company, just saw that and figured I'd post for comparison.