Never heard of them.
To be honest I would start looking at different chemistry now.
They are very cheap and I would trust that the bike shop know their products. This Weida I found their web site and its been lost so there is a good chance they are out of business. This doesnt mean the batteries are not any good, they could be awesome and the reason why they are cheap is because they selling the stock, but it could mean the stock is old.
Battery weight and how much charge is left after a ride and what voltage they settle at after a charge, do they balance when charging, and what is your bike going to do to them when you throw a good load onto them is what is going to be the deciding factor. An average battery in na 350 watt bike might do just as good as a good battery but die in a month on a big hub. Massive current draw can kill an SLA that could live as for ages as a solar lighting battery or for wheel chairs that go all day.
