I guess that the question is what constitutes an immediate return to land?
Do you mean a quick circuit to get the aircraft back onto the ground?
or do you mean something else.
let me preface the below by saying that each case is individual and I am talking in general terms here!
I brief that if we need an emergency return we will do a LH or RH circuit (as applicable) , nor a non emergency return we will go and climb up to the 25 nm msa, sort it out and then come back when we have our poo in a pile.
I reckon an emergency return is when the machine is burning, or has some sort of handling problem.
If it was a rundown or similar I'd climb up to the MSA do the checklists, brief the cabin crew and pax, brief the approach etc (not necessarily in that order for the pedants)
I reckon a major cause of stuff ups (in the sim at least) is people rushing and forgetting or not considering something that they would never normally dream of forgetting.
Taking the time to sort everything out, run all the appropriate checklists, speak to the required people, discuss amongst yourselves (Capt and F/O) the options, have we forgotten anything - any suggestions etc, is a very worthwhile thing to do in my opinion.
In my mind this is where I would make the distinction between a PAN and a MAYDAY.
The statistical probability of having a failure, followed by a totally unrelated failure of the other engine is incredibly remote - note the word unrelated...so much so that I reckon that the risk associated with taking the extra time to dump, do all the other things etc is outweighed by the risk of stuffing it up if you rush.
No matter what you decide on the day, the arm chair quarterbacks will come up with a reason why you did it incorrectly anyway - so why worry!