Again, purely subjective, I liked shadowflare on the GCD, and I honestly didn't hate manually applying dots, and it still felt different to BLM and RDM.
Devotion working like how I stated it there would actually reduce delay as it has no queueing or ghosting to worry about in the pet ai, as long as it came out with the summon cast it'd work the same/better. Only reason I didn't say have devotion on the summoner itself, is that imo a summoner should revolve around the summons.