What's the downside to buying myself a portfolio?

[Josiah Mann]

I've come across a few 100+ unit portfolios of single family and small multi-family properties in my local market that I'm interested in purchasing. The main reason for my interest in these specifically is that they offer owner financing and I don't have the equity or cash to get in another way at the moment.

My main question is, assuming I put very good property management in place, get a good price based on actual rent rolls and P&Ls, and due my diligence thoroughly (including inspecting every unit), is there any downside that I might be overlooking?