I went throught this process on my E53 a few years ago, I went with the All weather mat for a few reasons(its cheaper one at about $73), first it is very durable and strong, there is nothing you would want to put in the X that could ruin it (*) and fit perfect like a glove, it is light wieght 8-10lbs (nice rubber) an foldable if needed, and lastly it has a nice BMW logo in the middle of it(cargo mat doesn't) and everytime I open the truck there is a nice BMW sitting in the middle ....best OEM addtion I've made and bought the exact same mat again for my new e70 when I got it (fyi e53,e70 are shaped different)

...its a must buy for $70, looks better, protects back, and you never have to vaccum the back again just pull out shake out put back

*I only put this because they make a harder $250 version that is rated to handle a certain class of chemical slips/battery acids....but whos gonna really need that much protection