Terraterm is just a terminal emulator. You have NO IDEA how rich THAT environment is under Linux. I think you would be more than pleased with those choices.
Given that information, moving to Linux should be rather painless for you.
I would start by putting a Live ISO on a flash drive and booting up to that, and see if you like that particular flavor. If not, you can always replace that ISO with another one and reboot.
That way, you can test drive Linux and it's different distros to see which one best fits you and the way you work.
Have you tried Arch Linux?...I am looking at starting with it...I have decided in my old age to learn a new language. And I know very little about operating systems...so it is going to be interesting. I have a “new” refurbished computer to play with it on.
Or maybe I should go with Mint...?