I am running low on the Gillette Sensor 3 that I typically use, and have noticed that the prices of these cartridges seem to have gone up a fair bit. I am thinking of possibly using the Gillette sensor 3 disposables instead of the cartridges. Is there a big difference between the two? I also see that there are more than one type of Gillette Sensor 3 disposable. What are the differences between them?