John coughed up some electrons that declared:

Any negative experiences? I was thinking of fitting one to make turning
off the water a bit less fraught - I have had the stuffing gland leak on
my existing tap despite replacing the seal and keeping it lubricated.

I've seen a lot of positive experiences cited on various forums, but it's a
new device, so test of time and all that.

Did you mean you're having trouble with the gland on your stopcock? Or that
your stopcock is hard to get at when your tap goes?

Unless it's question of accessibility, how about a full bore lever valve?
Bit easier to operate and less to go wrong?

Cheers

Tim