If your running a hot engine (fast/powerful) and you don't want to look at your diffs for a very long time, the CEN diffs will give you that. Although, I think it was a bit more popular before HPI started including aluminum diff cups and 4-spider gears in each diff.
If you ever saw the diffs side by side, you'd see why they are durable comparatively. It's like seeing a gear assembly out of a ford fiesta compared to a gear assembly for a dump truck.
I agree, if you install a Savage diff properly it will hold up nicely.
One thing you can do to help the diffs live longer is to seal the skidplates to the diff housings. Dirt sneaks by and ends up in the gearboxes. A little silicone stops it.