Instead of another URL, I think having a per-account option would be better, since most people will be linking to lemmygrad.ml rather than old.lemmygrad.ml. (I don't personally care for the old.reddit.com UI, but I do like the one on Lemmygrad before the last big UI update)
Comradeship // Freechat
Talk about whatever, respecting the rules established by Lemmygrad. Failing to comply with the rules will grant you a few warnings, insisting on breaking them will grant you a beautiful shiny banwall.
A community for comrades to chat and talk about whatever doesn't fit other communities
It's not possible to do this under account settings presently.
perhaps a workaround could be to have a "redirect to old UI" option, so both lemmygrad.ml and old.lemmygrad.ml could check if it's set when navigating to a page and redirect if appropriate
I think the GUI is too different for that, since it is not a theme of the current GUI but something completely different that needs to be installed on the server.
That would be great too — would be neat if that could be incorporated into Lemmy somehow