A Tabula Rasa has no stats at all (unless its corrupted), so any armor will be an upgrade except for losing dps due to less links.

Can you add stats to a tabula rasa?

The entire theme of the item is that it grants no stats, so as a result, there's nothing on it to describe exactly what it does, which can make it a little confusing for players who find one while still new to the game.

How long should you use Tabula Rasa?

If you can manage to make up the lost resistances, life or energy shield, or even the unique affixes of uniques (which are incredibly strong and dominate life based builds), then you're free to use a tabula for as long as you like.