another reason single ply is the new king,maintenance areas should be budgeted to be covered with rubber walkpads in maintenance areas to prevent damage,unfortunately too often it all breaks down to the almighty dollar
For a properly trained crew who has the right equipment, I would still personally prefer a Coal Tar Pitch roof.
I installed many, many brands of single plys, and the main defect that occurred from one brand to another, was the maintenance and actual working staff going up on the roof creating minor damage.
But, a "Minor" slice in a single ply membrane is a 100% intrusion of water.
If the facility that is getting attended to had a dutiful, conscientious maintenance supervisor AND did not allow any other contractor or building employee up on the roof unsupervised, during the entire time that they needed to be up there, then the single ply roofs would be a much more resiliant system.
I love putting them down and also, they are much easier to install and to patch, in the event that a patch is needed though.