1. With Luma3DS you don't need to update to access theme shop or the eShop. 2. Why not wait until everything is fixed and working on 11.1 to update. Ya know, new HBL payloads and BootNTR updated for the new firm.
By all records (and me just opening the theme shop myself to check) you don't. It's one of Luma 3DS's features.
I'm on the latest Luma3DS, and it's telling me to update if I want to enter the Theme Shop's Purchased Themes section.
Now, DLC shops and such, that I could understand since that seems to be throwing the "wah update" error.