Comparing the Mach 3 to a Sensor is like comparing a Chevy Cavalier to a Dodge Neon. Both are worthless and neither compare to a Lexus (a DE).
You know I would have to strongly disagree that a Cavalier, or a Neon is worthless. I have driven both: they both got me from point A to point B, and sometimes that is all that matters. I have never driven an overpriced luxury car, and honestly never have any desire to do so.
On the same token, I don't think two bladed cartridge razors are worthless. Millions shave with them everyday, and seem perfectly happy.
I also don't think it is very welcoming to a newbie, to tell them what they are doing currently is worthless.
I do think, however, that anything more than two blades is overkill, and quite simply a total waste of money.