Most everyone uses a percentage to quickly analyse properties but each property is unique.

Rather than refinancing each property, after every rehab we just have a significantly higher percentage of equity in that property.

What percentages do you LA investors use when estimating opex while underwriting a property?

You can not compensate people for raising capital by giving them a percentage related to the amount of money they raise.

If you built the list yourself, the percentage of wrong numbers will be 5%-10%. 

Notice this is not cash on cash return, but rather percentage of rental income.

And yes, they charge the guest a higher percentage than me; however, most all of the local PMs also charge a booking fee of some variety if you book through their website, so it's not like that cost goes away or gets rolled into rental rates via a PM.  

Using the BP calculators to estimate expenses, I was curious to know what percentages other Columbus, OH investors were using for conservatively estimating management fees, repairs, vacancy, and cap ex.

Revenue: Gross rents then subtract all belowVacancy(5%)-Maintenance-if it's rehabbed this number will likely be close to 0 otherwise, budget another percentage (talk to investors in your area)Property Management 8-10% - CapEx-5% for reserves and big ticket repairsProperty Tax-Insurance-Debt Service (principal and interest) =Net cashflow pre tax

This is normally expressed as a percentage and that percentage is of the ARV.