Your use of Affinity Photo seems to be the big question. The 8/256 machine will handle the rest without breaking a sweat (and very likely everything you are asking of the machine). What are you currently editing with? How much RAM does it have? Are you running into slowdowns in your workflow due to excessive swap? Are these slowdowns long enough that it truly detracts from your work, or are you simply experiencing longer times producing your final product?

Photo Editing Feature List | Affinity Photo
The complete feature list and system requirements for Affinity Photo show you why it’s the first choice of thousands of creatives around the world.

8GB is the recommended configuration for Affinity Photo.