Two issues I had:
1. 3 times my emails to gmail will be "silently delivered" in that they don't bounce but they don't land in the inbox. I had it happen to me (sending to my test gmail), me sending to a friend, and me sending to a business. It's a gmail problem, but this never happened when I was on fastmail.
2. Jarland is a solid admin, but he's "old school". Sometimes he'll blanket ban incoming mail, and you might miss messages. For example, I was trying to sign up for mailjet and I wasn't getting the sign up email. When I opened a ticket, it was because MXroute was seeing "a bunch of spam from that provider" so it was blocked. I have no clue if I missed any emails from sellers/senders that use the service during that time...