But yeah, any feedback on this and whether I should repeat the formula would be great.  

There is no magic formula.

You have the basic formula correct above but it's a little more in depth than that. 

It is hard to be accurate when answering this question because we are not talking about a specific property with real numbers but formula here. 

Now, I'm not an unrealistic person and I know that not all formulas work the same for everyone, but I figure why not at least ask on BP to see if anyone has done this in the past and can offer some advice?

My guess is the answer is found within either networking with individuals that rent within the area or maybe there is some type of "formula" regarding looking at apartment/condo rental prices and using it to further understand single family or multi family rents.  ???

Can i ask @Ben Leybovich, do you have GRM formula you prefer using when buying MF? 

Also, the topic of reserves isn't as sexy as topics like "increase your rental income quick" or "my tenants just shot somebody".Generally my reserves formula is three months the rent, but I have a lot more because of my system.

Here's the 3 year formula from Steve Berges' example (Table 8.1):Net CFs from Investment 3 Yr Exit in Year 3 = Owner's Equity + Gain on Sale in Year 3 + Total Return in Year 3 + (Principal Reduction Year 1 + Principal Reduction Year 2)$599,692 = 175,500 + 340,000 + 56,021 + (13,541 + 14,629)You will do the same for a 5 year exit, but be sure to include Principal Reduction from Years 3 and 4!

One of the arguments I've heard is that, mathematically, the formula just doesn't make sense once you get past a certain level of ARV because rehab costs don't have a linear relationship to ARV.