Dear John,
Cloud hosting is effectively a possibility but personally, I only worked with private cloud provided by ovh.com that is far expensive than shared hosting that you mentioned.
Shared hosting should work as this is the kind of things that we used for many years with some customer as well as VPS and dedicated servers.
When working with VPS and dedicated servers, I recommend to manage the server yourself and have the root access to allow you secure the server as you want.
In general, we recommend using cPanel as administration tool but Plesk also works perfectly now.
A key element that we also recommend is to use the "weekly backup" with an export of the backup outside of the hosting company.
So that, if you have a problem with the hosting company, you have a rescue solution to restore the latest backup on another hosting server (temporally or definitively.
www.jms2win.com/en/component/docman/doc_...ackup-script-all-dbs
The advantage of Cloud solution is that you can grow as you want.
You can also have fault tolerance setup and high availability that might be available.
You can buy additional resources and create multiple virtual machine for different purpose.
The OVH "private Cloud" that we know, is based on VMWare technology but is very expensive.
For just 4 clients or websites, this is not recommended.
I think that for 4 websites that would not be required except if those websites have a large traffic and very sensitive that could justify such technology.
The VMWare technology and OVH private have a firewall that can be setup outside the Virtual Machine that you will setup.
www.ovh.ie/private-cloud/
The fact that we provide a link to OVH does not mean that we recommend this hosting company.
You need to have a lot of skill to manage such kind of servers or technology yourself.
If you don't have such skills this may result that you will have to pay more to get support and assistance.
We just mentioned that to illustrate our experience with cloud and VMWare technology.
At the end, in most cases, this result by using a Virtual Machine ruining under CentOS with WHM/cPanel for the administration.
I hope this will help you deciding the kind of technology that you would like to use in the future.