Sounds like you are either very unlucky, or have a useage pattern (or install problem) that is triggering issues. I'd definitely try and work out why they failed before pulling the trigger on another machine, no matter what the make, unless of course the failures are obviously defects, in which case i'd be complaining to Miele and seeing what they can do about it.
Tempted to go for something cheap and throw it out every 2 years and save a lot of money.