Yes, many monsters above your level are challenging on Death March, especially beyond level range. Even enemies slightly lower level than Geralt if in large groups or under the right circumstances, a group of level 20 monsters can be a tough fight for a level 22, for example.
Concerning armor, Ursine is also a good choice for an adrenaline build, sacrificing the better offense of Feline armor and some stamina regen (negligible for adrenaline build anyway) for high armor rating and a very good resistance to damage from monsters. Good with the skills Undying, Whirl, Rend and Flood of Anger. Looks nice aswell, if you like surcoats.