The K16 carries my 100 kgs up steep hills with only the single gear. It can do that because it was designed to be a powerful bike up to 15 mph,it has a small chainring and the motor in the 16" wheels has a strong torque reaction.
The K16 was designed to be nippy in an urban situation,but the pedal cadence will be high if you are always going fast....to keep the weigh(15kg)t light allowing it to be easily carried on a bus or train you have to compromise on some details.
The K16 has such powerful acceleration that we did consider at one point reducing the power but riders soon get used to the power,you will have no problem climbing steep hills.
In contrast the Kudos Secret has the same motor,but the motor is inside 20" wheels so the torque reaction is lower, however it has gears with a larger chainring so you can change gears to change the rider torque and have a lower pedal cadence at speed,this does however add 3kg to the weight (total 18kg)so it's not so easy to lift on a bus or train.
The K16 and Secret have clearly defined uses,you do have to be careful to look at what you want the usage of the bike and select the one to do your job.
Both bikes have the same 10,4 Ah battery which will give 30-40 mile range.
Hope that helps,you do need to try a bike,you will soon realise which one is right for you,both bikes are selling very well at the moment,the green colour is very popular.
KudosDave