LiveM: Over the last couple of days I have tried a few scooters, and found the Zero 9 (1200W) is the minimum for this kind of hill. However, the Zero 8 and Ecoreco L5 will handle a slightly lesser grade pretty well.
For me the L5 is about as massive a scooter as I would want, and I preferred its bigger deck. The Zero 8 is a little larger and power felt the same with 768W & 960W respectively in their specs.
The suspension on the L5 and Zero 8 are both absolutely fine. I had not expected that with the solid tyres and the L5's spring suspension. I took them over the Victorian-era cobblestones around Victoria Park Market with much missing grout as well as various obstacles on footpaths and roads nearby.
Now I remember that the Zero 9 is bigger than the Eco Reco L5 and I was comparing it more with the Zero 8.