The first question is were the Lemfoder and Myle parts bought from a authorized Lemfoder and Myle dealer or a general seller? Before condemning a entire manufacturer be sure the bad parts are not counterfeit.

Lemfoder is a OE manufacturer for Mercedes and others.

Something I've found that will increase boot life. Add some lube between the boot and stud so the boot isn't flexed so much as the joint rotates. A bit of lube between the top of the boot and steering arm / spindle helps things as well.