Don't remember ever seeing that question come up myself.
And not sure of the answer either, but I'd say that the one with no play has the advantage here!
Not sure just how much play we're talking about here though. I've seen some play in just about all of them. Seems to met that the two locations for reducing that would be with the rear output bearing and the individual roller bearings at the coupling between the input and output shafts.
So, how much play are you seeing in the one trans, and what is the debate about using one or the other? Why not just use the one that you think is the better unit?
And when it comes right down to it, if you're not pressed for time too much, they're an easy rebuild. I did mine as the first gearbox I'd ever opened up and it went smooth and easy. Couple of small frustrating spots, and a couple of new tools I needed (and have used on other things too), but overall very straightforward.
Paul