For me, the snoozing function of Spark has almost become indispensable in my workflow. I do wish that Apple Mail would implement some sort of similar feature.
I see. I never got into snoozing because I check most of my email on my desktop. That's why I was so excited that Spark came to desktop, so that I could start using Snooze on the phone and resuming on the desktop. I'm itching to get back to Spark and hope they get the IMAP bug fixed. I sent them videos with Apple Mail and Spark side by side, with Spark showing less emails and not fixing itself with restarts or refreshes. :-( They've told me they are looking at logs and trying to figure out what's wrong with Spark...
For now, I actually enjoy Apple Mail. It's a lot better than it gets credit for. It's just missing snoozing, a slight UI redesign and some better Gmail notification support to make it excellent.