V-brakes have excellent braking power and control and would be
fairly easy and inexpensive to install on the EcoSmart scooter when compared to
disk brakes, To add front V-brakes to the Razor EcoSmart Metro electric scooter the first step would be to bring it into a bicycle repair shop and have them weld V-brake bosses onto the front forks. Then the front forks would need to be repainted and a V-brake, brake cable, and brake lever with built-in brake switch installed. The EcoSmart scooter's controller has an extra connector for a second brake switch that the new front brake lever switch could be plugged into to complete the installation.
Although caliper brakes would only require one hole to be drilled into the front forks to install, which almost everyone has the tools to do themselves, they have extremely poor braking power so I would not use them on an electric scooter. Caliper brakes barely have enough braking power to stop a small children's bicycle and they are just about useless for stopping electric scooters. I am speaking from experience here because I installed a caliper brake onto the first electric scooter that I custom built and it took forever to stop, even with both shoes dragging on the road trying to help.
Old post but thought I'd add what I've done while I'm thinking of other options. I've had this setup for several years now and it works great. When I first got my scooter I worked at making it lighter and have less rolling resistance. Things I do to bicycles. I replaced steel parts with aluminum and replaced the stock tires with 1.5" Kenda high pressure tires. The smaller tires allowed me to install a short-reach side-pull caliper brake. The stock tires require a long-reach brake (I tried one) but the braking power is peer due to the reduced leverage. The trick to use the short-reach is the use of a home made drop bolt. These were used way back in the '60's on bicycles that were made for long-reach brake bikes to allow the use of the better braking of the short-reach version. Back then you could buy factory made drop bolts but those are long gone. You can make your own as I did. My current issue with this setup is I now live where the streets are very rough and my narrow high-pressure tires give a pretty rough ride. I'd like to go back to a more stock type tire but I need to find a front brake solution first. The front fork is a standard 100mm spacing. I replaced the steel front wheel with an aluminum one. The rear is 130mm and will not fit the front. I'm curious if you came up with anything? If I figure something out I'll post what I did.
A well-equipped bicycle repair shop should be able to weld or braze cantilever brake bosses onto the front forks so that v-brakes can be installed.