@Coyote @tyil I've had this discussion many times. Some people have no problems, other people have nothing but problems. A lot of it is because of what IP block you're coming from.
I worked at a company, we had the same IP range since the 1990s. Manageable spam, deliverability good. We had way too big of a block of IPs so we sold it and bought a smaller block. That block got continuous spam and deliverability went into the toilet. After a year of fighting it we just got gmail for business.