That might be true for usage, but if one needs to put backup somewhere else it might take ages. If it’s with rsync it might be fine but with 1 cpu core it takes also ages 
I might use one of the bigger storage VPS as secondary backup storage though. Quiet cheap 
Here are Hetzners Storage boxes, also cheap and fast (as it’s via WAN, no traffic): https://www.hetzner.de/hosting/produktmatrix/storagebox-produktmatrix
How is it about stability with those VPS?
One year back we used Contabo VPS with 2TB drives, they were unavailable all the time and the discs where corrupt once or twice a week. :-/