I m a sucker for the 16520 because it is such an easy and comfortable watch. It is nice to see that you follow your own mind on the references and not be taken by all the hype around one specific model. The SD50 is nice but also quite big on the wrist. It is smaller that the deepsea but bigger than the old SD. The SD50 is watch that feels like armor. It is a solid watch. If you want to stick to the explorer theme, then that is the easiest for availability because the Explorer II is currently the only ss model that is available in stores. Too many choices my friend !