I have had section 8 tenants in both SF and apartments. We still have a few legacy section 8 tenants. Since they have been good residents, they can stay as long as they like, but we are not accepting applications for new section 8 residents. Otherwise, our properties are now 100% market rate.
Why? The reasons are many.
1) My top reason is that I can't stand bureaucracy. If you invite the government into your business, you get the good and the bad.
2) In my experience,(and I may get some hate mail for this) the average section 8 resident is harder on the property. I am speculating as to why, but it could be a lot of different factors. Perhaps it is because hey have none of their own money on the line so they may not care for it as much as someone who does. By definition, they are from a lower income bracket. While there are amazing and awful people at every level of income, generally the lower the income, the more likely you are to have a rougher tenant. Being harder on the property means more intensive repairs & maintenance, particularly on a unit turn.
3) If your focus is just cashflow, this may be a good strategy because the tenants tend to stay longer and the rent is backed by the government. However, I like to focus on both cashflow and appreciation or forced equity. I do that by upgrading the property, making it a more desirable place, which often allows me to get higher rents too. That is harder to do if you have a rougher tenant base.
Related to the above, I've had much better experience with section 8 residents that pay a portion of their own rent. They seem to be more responsible, and the setup gives you some flexibility that you don't get with either market rate or tenants with 100% paid by section 8.
We had an elderly woman who was partly section 8 and her rent was $200 below market. We applied to section 8 for an increase and they said they would pay $150 of it. We did not want to raise our tenant's out-of-pocket by $50 so checked and were told section 8 would pay $150 more regardless of what we set the rent at, so we only raised the rent $150. In this case, we got to keep a great resident, give her zero rent increase, and also improve the financial performance of the property.