The importance of customer services is directly tied to how:
1. Handy you are, and your set of tools to make things right.
(Good set of wrenches and a multimeter, check).
2. How "standard/available" are the parts available online.
(typical Hailong battery, check. Standard Hub motor, check. Standard YF series display, check, standard 7 speed derailer, check. Common brake system, check).
I have bought 3 online. If something minor happens, most are just wrench time with no significant parts cost.
So far, my repairs have been:
1. Seat screws stripped out when I tried to lift the bike by the handlebars and seat. Those were replaced with a longer and larger diameter screws, fixed. Less than 2 dollars cost for two screws and upgraded washers.
2. Reflector fell out of the pedal. It was a press fit reflector, It was pressed back in. (It fell out when the seat came off in my hand and the bike bounced hard). Free.
3. Flat tires. This was addressed by going to thicker carcass tires and putting "flat-out" in the tubes. No more flats. This is a common problem here; this would be true on any bike. Manufacturers don't warranty against flat tires.
4. The factory rear shock on one bike was far too stiff. This was a design issue, it was non adjustable. I ordered an adjustable shock and installed it. Total cost about 70 bucks, but this was a better than factory shock.
5. The inexpensive cloth saddlebags tended to curl into the tires. A horizontal brace was put on the rear rack (towards the bottom), to keep the saddlebags from curling in. I used bar stock I had on hand left over from another project. This would not have been a warranty issue.
All three bikes are currently running without issues. (Zeegr, Zeegr, ACTBest). I have another online bike on order. (Motor Goat v3).
But, if you are not handy, and you have the free cash, the most worry free choice is buying from a brick and mortar store. Do understand when you do this that many bike shops are financially stressed, and may not exist two years from now.
Another issue can be ran into if you relocate. There may not be a dealer network a few hundred miles away.
There is a post from a man with a Merida eSpeeder 400EQ in the forums right now. His bike won't boot. It is caught in a looping boot cycle. It is a very nice $3000 bike he bought in Ireland. He has moved out of the dealer zone, and is having real issues getting his problem addressed.
