Hmm... it's difficult cause robes don't give enough warmth to survive in northern Skyrim and Legendary is already pretty tough against Dragon Priests or high level Draugr (at least for me)
Edit: I play with Frostfall and my hunter uses robes for warmer regions and fur armor with a fur hood and cloak in cold regions
It's up to you, but I wouldn't submit to a Dead is Dead playthrough unless I was absolutely sure I'd enjoy it. Sometimes, playthroughs like that end up becoming quite frustrating if you don't know or don't have the time to manage it properly, and gaming is not supposed to be frustrating.
So do it if you can take it and have fun. If not, don't. Personally, I'm not a fan of it.