My initial impression of AP is very, very positive. Good layout. Great tutorial videos. I've used PS a lot but AP appears to be far more user friendly. AND it's a very reasonable one time purchase instead of the bloody stupid subscription that Adobe uses. I hate subscriptions for software! Cross-platform is awesome--not that I use Windows anymore (avoid it like the plague) but I have friends and family who are still on it.
I've been using Macphun's Intensify, Noiseless, and Snapheal CK plugins for Photos, which has been reasonable enough for most tasks. But I've had several problems with database corruption in Photos. If Affinity can create a DAM software that is as good as AP AND that integrates with iCloud sync that'll be wonderful.
Admittedly, I miss Lightroom. It's more powerful than extensions in Photos. But I could no longer stomach the monthly subscription fee. I also really wanted the ease of taking pictures on the iPhone and having the images show up automagically in on my MacBook. (Not that their syncing isn't without its issues.)