Well like I said, when I looked for a computer to buy I first started looking on the algo then on the software implementing this algo. At this time vpm was only available on the x1. I do understand that SW has now implemented vpm toped with GF but again it's also available on the x1 as well as vpm-b, vpm-b/e, GF, vpm-b/GFS. I would also add that v-planner is an excellent dive planner, there's not a feature not available for you in it, it's very technical and a pure pleasure to plan deep dive. That's for the software part.
As for the hardware, I'd compare the x1 to a hogarthian configuration, it's straight to the point: no oring so no failure point. On the SW you also need to change the battery witch has an oring too. The x1 is potted, water can't penetrate it.
It has 2 ceramic sensor, it's small and yet the screen is amazingly readable.
You connect it to the rebreather by infrared again no failure point.
It has no button that could break or stop responding or be difficult to use with thick gloves.
The above is my personal preference, some people like donut bc (like me) other still dive shoe horse style bc. Some other dive dir or hogarthian and other people some other configuration.
Don't get me wrong the SW is an excelent computer. I just found the x1 perfect.