What's the best way to compare/analyze turnkey properties?

Three things:Appraisers can't compare SFRs to duplexes any more than they can compare duplexes to space ships.

Right now, I am getting 2/3 times to return on my investment compared to QRP.

You should speak to a lender first and see if how much in loans you can qualify for and then compare that amount to the neighborhoods and property types in Los Angeles.

If you compare like for like, sfh are more profitable.  

Don't compare yourself to others and find what works for you.

Again, I am completely unaware of comparable offers, however this duplex seems to have many really wonderful amenities and it is newly refurbished.

Nothing compared to property purchase cost increases over the past few years. 

Most agents put the best house, with the highest sold price that is somewhat close to the subject property, and call that a comparable.

County tax values are not relevant really a good indicator of market value.Though you do need to look into the current inventory, what development is happening in a neighborhood, and how many sales occur in that price range compared to # of houses in inventory to get an idea of where you can land compared to the comps.