“We will have to send subscription e-mails out when a post is made. I worry about over-spamming a user with a busy thread, so I need to perfect a method of flood control, whilst still working without CRON.”
An alternative would be to provide some sort of control panel or interface where the site owner can manually choose when to send email. That way they're responsible for the schedule. They can do it once a day, once a week, or every 5 minutes depending on their needs. They could also choose which threads/feeds to send to which lists.
Automated email is a delicate issue. There are specific legal requirements involved in managing lists, server settings involved in avoiding spam filters and blacklists, and a whole lot of other trivial but absolutely necessary details involved. To my mind it really is something best left to an external service.
No matter how much parents love their children, they cherish the time when they're asleep. It's a tragedy when it gets interrupted. "A sleeping baby is a gift from God."
The best advice I know of for family sanity is a regular schedule. Regular mealtimes, regular naps, regular baths, story times, bedtimes, and bedtime rituals. Don't overlook the value of good naps. A well rested baby sleeps well at night. But advice is just talk. In the end you get what you get and you don't pitch a fit.