They recently installed a 4 bike version at The Bicycle Academy. During the week of my course there, and I was riding my 27kg e-bike. It had no issue holding the weight, and as long as you don't mind lifting a bike 'backwards' you can store them very close together.
This product pinged up on my Insta account. Looks like a great system but a bit pricey. Anyone heard of it or used it before?
https://www.stashedproducts.co.uk/pages/shop