Linux is Linux it doesn't matter... at most the difference when you install ET could be 32bits vs 64bits.
I don't use ETLegacy and btw it doesn't work with ETpro, and not only for playing, keep in mind that ETTV is etpro as well.
For example this Sunday there is the final of ET nationscup Ned vs Fin, what if I wanted to see it? I would need etpro, and with etlegacy I wouldn't be able to see that match...
What's more, I don't know what he meant with 'automatically download the needed pak files'... after you install standard ET 2.60 you already have the basic pak files, the only thing you will miss are custom maps, mods, pk3s from specific servers, etc.
You can download them from the servers when you connect, or you can mass copy those files from your Windows ET install into ~/.etwolf (/etmain, etc.etc.)
Actually when I used to dual-boot (because of etpro+slac), I was tempted to use the same folder for both Win and Linux via symlink or similar ways (mount with bind, etc.) but I decided to stay with 2 separate installs because of slight differences in my config (mouse keys like mouse3 have a different bind in Linux).
When I moved from Fedora 32bit to Arch Linux 64bit I didn't even reinstall ET, I just used the same folder (my ~/.etwolf is a link to another partition so I didn't need to copy it)