I am just starting to use Scrivener. I have a 24-inch iMac and an iPad (Gen10).
I am aware that there are differences in Scrivener between the way it works on an iMac and on a iPad. Also, Apple has some issues with syncing to an iPad.
It seems to me that I should use a MacBookAir if I may be writing on the go.
I am looking at getting a 2017 Intel MacBookAir from Back Market. It should handle its mobile assignment for Scrivener.
At this moment, I’d say stick with your current gear. Just follow the linked instructions to the letter and it will be fine. Scrivener iOS is fine for writing, do all your compiling on the iMac.
Keith has mentioned on the forum, a new writing app under development. We’re not allowed to discuss details of the beta, but from his public statements, it will sync with iCloud and I think it may provide a better mobile experience. No release date, and L&L won’t give any estimate of that so base you current decision on what’s available now.