Also, they will have taken their rental return into account, which carries on! 

What would you say I should be making for a cash on cash return for a 9 unit multi in a great neighborhood - with great tenants?

I think this is why internal rate of return exists - I know we're talking about rules of thumb, but if I've got a property in an area expecting lots of rent growth, I can add value in other ways, etc. over the course of a few years, the present value of those future cash flows and any other liquidity events become very important and it could make sense to accept a much lower CoC in the near term. 

Honestly, with those returns sounds more like a D/F area.

That will give you a good indicator of whether to keep it or not.If it's a good returning property then a refi might be warranted. 

What’s the cash on cash return?

I understand that I would get penalizes 10%, and I would have to pay tax on the money as extra income, but if I find a real estate investment that has a return of 8-9%, I can have the 10% penalty paid back to me on the first year of owning the property and then I can utilize the future returns right away rather then waiting till I'm 62 with 401K. 

I purchased a quadplex with great returns and I'm holding on for the long run.

Small hacks that can help my returns?

If it's not going to keep moving upward at a fast pace, 0.3% rent to value is a terrible return.