IMHO the breakthrough innovation for cartridges are the spring mounted blades that were introduced on the Sensor, my most frequently used razor. My skin is far from perfect and that particular feature provides me with close comfortable shaves.
I use a variety of razors including DE and Fusion. I always come back to the Sensor. It's the best for me.
Sounds like you found your perfect razor. Did you find that the Sensor carts seemed to degrade in quality as the M3 and Fusion where introduced? Some swear the older models aren't as high quality as they used to be.