I guess I need to remove Vesta completely before installing Hestia?
All I can think of is stopping & removing the vesta service, removing vesta packages and removing all the admin v-* cronjobs.
I would really appreciate a step by step guide to take me through the entire process.
We do not support an “move” from Vestia to Hestia. We suggest always to do an full reinstall as we setup multiple things different regarding VestaCP.
v-backup-users
Backup files to save location
Reinstall OS / Last OS
Import backups
v-restore-user user backup
I reaaaally don’t want to reinstall the OS 
I’ve got so much other stuff running on the server that I’d need to setup again.
If someone could provide a guide that doesn’t involve re-installing the OS I’d really appreciate it.
There have been so many changes in Hestia that we can’t guarantee a safe switch.
If you really can’t/want to reinstall and your are running Debian you might consider myvesta https://myvestacp.com. At least that one get actively patched and has multiple security features…
This will convert your Vesta to myVesta > https://github.com/myvesta/vesta/blob/master/src/deb/for-download/tools/convert-vesta-to-myvesta.sh although I must attest that HestiaCP has been rock solid for us.
Unfortunately I’m on Ubuntu
I moved from Vesta to Hestia with no problems. It’s always a bit of a pain to do a fresh install when you have so much set up but at least it keeps your Linux admin skills sharp. Just make sure you don’t forget to back anything up!
I think a reinstall would be the best, if not only way to go.
Good luck 
It’s not just re-installing & configuring loads of software, it’s the sheer size of stuff I’ve got stored on there, and reinstalling the OS with my server I’m 99% sure will wipe my hard drive… It’ll take me several days to upload / download the lot to preserve my data.
If I uninstalled Vesta (while leaving most of its components) would I likely run into any trouble (ie, conflicts) if I then tried to install Hestia?
Has anyone managed that?
No official support and never tried. Why not order a separated vps/server and migrate it user by user? Yes, you need to change the server ip in dns, but downtime would be minimal.
Not to mention the extra cost… and I’m not bothered particularly about downtime.
Considering I only want to upgrade for security updates it just doesn’t seem worth all the hassle if a complete server reset is required.
The existing exploits in vesta are critical, vesta is dead. You’re right with additional costs, but usualy this is “just” a month. You would need to do anyway a full backup, doesnt matter how you want to try it.
Vesta can’t be migrated to hestia, a clean OS is a need to gain any support. You can ofc try out whatever you want, but you should also calculate risk and effor. Stay on vesta is probaly a bigger risk, due to it isnt maintaned anymore and has unpatched exploits. Compared to the effor and costs you need, a fresh installation on a separated vps is probaly the best way to go - at least in my point of view.
You can rent a VPS in Hetzner Cloud and pay by the hour. If it takes you from some hours to a couple of days to transfer everything top the new VPS, then the cost will be less than 1 euro!
If you absolutely need to use your current VPS / Dedicated / IP address, then you can spend a couple of days more, reinstall the OS on your current VPS, install Hestia from scratch and then move everything back from the temporary VPS to your main VPS.