Tried and tested - the technique works, just that you need extra vetting when it comes to that expired domain respectively. Also, the expired domain may provide less of a link juice, try those that are pending expiry, which are still being held by the domain registrar, those would have much better link juice as compared to the expired one. Normally the expired ones have already been vetted by the pros - it's tough to find a good one, as a good one is normally grabbed at the pending expiry stage by others who are doing the same thing as you. You'd be amazed at what some of these pros would pay for these pending expiry domains. If it does not add value, then it shouldn't reflect the high amount of money that they are willing to bid for the pending expiry domain. So with the high payment involved - I'm sure you can take a hint at the value that it can contribute. I normally use TF>25 and PA/DA>35 as my initial metrics when vetting for a good expiring domain.