What ends up being the limiting factor for multiple MNs on one VPS? Is it the memory needed to support the daemons? The potential future network traffic as coin popularity picks up? Or even the increase in CPU utilization?
@CliffonCrypto You mentioned in one of your early MN videos that you were experimenting with 10 MNs on one server, but I'm guessing that wasn't a $5 VPS ... 
I've installed 4 MNs on one VPS and thinking about the fifth and sixth. Looks like I can easily start a new instance on Vultr and billing will adjust accordingly. Just wanted to think through these questions with this group.
Also, is it a better option to add a new instance? Or to increase the specifications of the existing instance to support more traffic (i.e. more memory, another virtualized CPU, etc.)?