I purchased an iPad version of the Affinity for my Pro 10.5 today (10.3.3.). Kind of feel a bit dissapointed with regards to the stability of the app. For a few times in first 2 hours of usage something froze in a process while altering an image, leading to a manual restart. Once the app crashed and closed for no apparent reason, once it crashed and the project became unusable at all (could not open it again). It feels a bit slow applying changes as well sometimes.
I really hope that you can improve the overall stability with future versions as I like the features, interface and generally I see a great potential in it.