George -
I've had a failure rate of about 20% with the gate valves normally
used for
water line shutoff valves. These are brass valves made in China or
Indonesia.
The usual failure mode is leakage around the shaft collar.

These are not cheap gate valves - at least the ones at HD I looked at.
They were 1/4 turn positive-stop ball valves with teflon or HDPE seals
thruout, and a good flow area. The ball appears to be stainless, and
the body is brass. I accept that they are not cerified and will
probably always be illegal, but I also understand the originator's
frustration. The older aircraft ones I've seen are really absolute
junk compared to these.