A 10% vacancy rate has the potential to knock the yields around significantly, which is why I think posting yield figures that are calculated solely from median property sale price and median rent are useless at best and misleading at worst.
Many property holding costs are roughly the same (or the differences are reasonably insignificant) like council and water rates and insurances. Expenses or other factors that are likely to significantly effect yields should be considered like vacancy and strata fees (if any).
If we're talking properties in Sydney metro, then vacancy is almost a constant EXCEPT if the property is a managed apartment, where it could have 15% vacancy -- a huge hit on the yield. Similarly, units appear to have fantastic returns until the $4,000 a year strata fees are taken into account.
So if you're looking at yield, always ask about strata fees and vacancy and take these into account at the very minimum.
If a property was also going to be difficult to lend against and will result in needing a larger deposit or higher interest rates (say, regional property or very small units) then these addition costs should also be considered.
The aim is to compare apples to apples.