Play is an issue, yes! And that would be another pro for fixed UJs.
But this has to do with position of the pin and the angle the dogbone has with the wheelaxle and diff outdrive. The smaller that angle (where 180 is straight, 90 perpendicular) the worse this effect gets.
To get the idea, take a wheelaxle with you left hand, insert a dogbone with your right and bend them in the smallest angle you can. Then rotate the dogboner. Does the wheelaxle rotate smooth?