I just spoke with Stan at Murray's. I'm impressed.
First, buyers of this product from Murrays enjoy an unconditional money back guarantee. "We stand behind everything we sell, and not just for 10-15 days. If you've got a person out there 6 months and he's not happy; we don't want that."
Whew! Refreshing attitude.
Second, the trouble seems to lie in trying to make a kit that fits all boats - a near hopeless task. Nobody except me has called them to report any trouble, but when I described this thread, Stan became quite concerned and said they'd investigate appropriate shims and instructions.
Stan was patient, concerned, polite and not in the slightest way defensive or dismissive.
The issue of corrosion was also addressed, albeit, with somewhat less urgency than "first-use failure" engineering concerns.
I'm sorry I was a tad harsh.