Its quite stunning how much better the E1 is with Li ion. But I think the forthcoming Factory Li ion will be a lot more expensive. I guess the choice to go Li Ion depends on how long you intend to keep it. The rangers I have done are from 2012 right up to a brandnew 2019 model that had done two weeks use. Most Ranger owners seem to hang onto them and be farmers or land owners (although one customer has 4, all used for virtually silent Camera tracking work) So for them the upfront investment pays off. It is possible to do a smaller pack, but I think thats less good option. The under load voltage on Li ion , with a decent size pack, is so much more stable. These particular cells dont drop much at all under load right through the charge cycle, which means the performance does not drop off as the pack goes down. I have to re programme the Sevcon motor controller so that it cuts back in a series of steps as you get near to the lowest voltage I want to take the pack down to. So its not an all or nothing setup. You do get some warning. Getting up to the pack size of the Ranger conversion just isnt possible within the space there is under the seats. (Ranger uses 8 cell blocks so 240ah rather than 180ah) . Im sure the Hisun is lighter than than the Ranger, so its probably not significantly different in overall range. I do know people who have tried off the shelf Li ion Battery replacements, but they are not so successful requiring separate battery chargers for each 12v block. They also tend to be Lifepo4, which doesnt burn if all goes horribly wrong, but in use the voltage sag under load is much greater. Lifepo4 can deliver huge currents, but they do voltage drop a lot.
A lot of the Ranger owners despite doing proper battery watering are seeing them last under 2 years of regular daily usage. They have an approximate 500 cycles life so thats not far off the two years. A few do / have replaced the odd battery, but on a n older pack once they start to go they will all go, a bit like triggers broom, my pack is 6 years old and none of the batteries are original.
My biggest surprise was on first going out in the Hisun, just how good the ride is. The shocks are an expensive item, but are worth every penny over rougher ground.