I've had a few sails with the new locosys strap extender, it looks a lot stronger than the much cheaper ebay version.

The locosys one on the left has much more rubber around the buckle pin, this looks very similar on the other side of the strap. (This where John's ebay version broke).
Only downside is, it's a bit shorter.

With wetsuit and spray jacket on I can still wear it on the middle of my forearm, but it's on the last holes and the end of the straps don't go into the retainer. My worry here is a knock on the end of the strap could undo the buckle. However I think it's always a good idea to use a lanyard.
My worry here is a knock on the end of the strap could undo the buckle.
Just use 2 of them?