We currently run several applications on a large SingleHop server and are not happy with service interruptions, cpanel, and the downsides of applications having to share some configuration.
Digital Ocean promised IPv6 support and the ability to run custom kernels several years before they provided this support.
2. Is the networking secure?
The "Private IP" addresses in Digital Ocean are accessible to anyone in the same zone.
3. Will they cover your ass?
https://motherboard.vice.com/read/nra-complaint-takes-down-3...
[0] https://aws.amazon.com/about-aws/whats-new/2011/05/24/elb-ip...
Also personally I find V6 more useful under the fold. For a gateway it's nice to support but doesn't give you anything. In your intranet it makes address conflicts go away forever and lets everything autoscale with zero configuration. This can be done with V4 but less conveniently and with more complexity under the hood (and therefore more things to break).
Pick 2 hosting solutions you like (I'd recommend checking out AWS, Linode, Rackspace, and GCP), and build your systems redundantly on both. If they don't share infrastructure/datacenters, the odds of them both failing at the same time are small enough that it's not worth worrying about.