We've had a pair of these for nearly five years now and it's only in the last couple of months that they have worn out (the flexible parts of the straws have developed holes). My girl is all girl and my boy is all boy, and I'm pretty confident these cups won't change that happy balance. I've always disassembled them completely for cleaning, and when the straws have mold growing in them, a soak in a 50/50 bleach/water mix fixes them right up. Anything stuck in the straw is easily removed with a pipe cleaner.
Like I said, they're only now wearing out, so I'm in for a set. At $2 per after shipping, it's cheaper by far than getting replacement straws.