I currently use the same Mach 3 I've been using since I turned 18. I've tried the Quattro (waste of money) and I've tried the Fusion (waste of money AND it made my neck go CRAZY). I've noticed some improvement with a mug and brush, but I know now that the best thing I can do for my face is use a nice sharp DE and practice.
Whenever I think of using my Schick Xtreme 3 on a daily basis I, fortunately, go on a trip. I am trying to use up the several disposables and packs of X3 cartridges in my travel bag. A couple of days of shaving with Edge and a plastic razor make me long for the future time when I have my travel case loaded with my minty SS and some Astra Superior Platinum blades. Over Xmas, when we were visiting family, I used a Bic Advantage disposable for a couple of days. An absolutely grim experience.
I still have the collection of Fusion cartridges that I bought before switching to DE. I still use them for the last touchup or to get the back of the neck. but once that suppy is gone, which will be years cause they never get that much use, no more cartridges. wife is getting ready to go DE when she gets over the fear too.
I haven't used my Sensor since I first used the 3.00 Tech I got last month and found some 1.80 blades for it at wally world. I came here to TSD and got brave enough to try it out. I've been given a couple more DE razors and bought a couple more and I can't see going back to those cartridge scrapes and rashes EVER.
I haven't used a cartridge for at least 10 years. For my head I use a disposable, but eventually I would like to use a DE for that as well. I have already done it a few times.