You have perseverance sir I will give you that
Just throwing another idea at you, and totally your call.
You had expressed an interest in ultimately running 3 - 4 Linux, you could throw one on now, and provided the hardware is not a limitation, that should work.
If you choose another Ubuntu-based Distro such as Ubuntu itself (I would suggest Ubuntu 16.04 MATE, not Unity, it's more friendly) or eg Zorin OS12, you will still be in the same "Family" for learning purposes.
You could choose one of the Fedora Workstation group, they are very stable, but you would be mixing and matching Debian-based with RPM-based - not a problem for the computer, but if you use Terminal, commands can differ in syntax somewhat, a double learning curve.
What will happen is this - the new Distro, as a part of being installed, will perform what I call TLS - The Leaderboard Shuffle. It will take over the top spot on your Grub Menu, with Linux Mint at second spot.
As far as the install goes, process will be almost identical (Ubiquity installer for both options), and you would choose the option (it will detect the Linux Mint) Install Alongside.
Have a think about it & I can field any questions. If you are successful in getting the 2nd one installed, the first will likely "come good". I can show you from either of my two main computers that many Distros can live happily ever after, side-by-side.
Cheers for the evening
Wizard
Just throwing another idea at you, and totally your call.
You had expressed an interest in ultimately running 3 - 4 Linux, you could throw one on now, and provided the hardware is not a limitation, that should work.
If you choose another Ubuntu-based Distro such as Ubuntu itself (I would suggest Ubuntu 16.04 MATE, not Unity, it's more friendly) or eg Zorin OS12, you will still be in the same "Family" for learning purposes.
You could choose one of the Fedora Workstation group, they are very stable, but you would be mixing and matching Debian-based with RPM-based - not a problem for the computer, but if you use Terminal, commands can differ in syntax somewhat, a double learning curve.
What will happen is this - the new Distro, as a part of being installed, will perform what I call TLS - The Leaderboard Shuffle. It will take over the top spot on your Grub Menu, with Linux Mint at second spot.
As far as the install goes, process will be almost identical (Ubiquity installer for both options), and you would choose the option (it will detect the Linux Mint) Install Alongside.
Have a think about it & I can field any questions. If you are successful in getting the 2nd one installed, the first will likely "come good". I can show you from either of my two main computers that many Distros can live happily ever after, side-by-side.
Cheers for the evening
Wizard