A couple of points:
- The keyhole spreader bar is only 10" wide, stock width for a Magic Marine spreader for L or XL harnesses is 12". The narrower spreader bar isn't nearly as comfortable for long days on the wire.

- Keyhole spreader bar is ~$150 each and you have to buy the ball attachments for $30/pair; add shipping, you're up to ~$200 on top of the cost of your already expensive harness.

- Now figure that the crew and skipper need to be able to trade wires when going downwind; double the cost from above.

- If you sail on multiple boats/multiple skippers/crews; now you get to change spreader bars depending on the boat and get used to the slight change that each system requires in how you hook up and release. The setup that we use is minimalist, but I can use it blindfolded; missing and falling off sucks.

- Keyhole system doesn't fit all harnesses; e.g. Zhik T2, Magic Marine Viper.

I'll admit, the current Magic Marine quick release spreader bar that I have doesn't instill a lot of confidence and I need to order a new non-release one. I've seen people get separated from their boats due to a failure in their spreader bar and/or trap ring; one of them caused a significant hand injury. I'm more worried about having a failure, taking a swim and getting separated from the boat than I am getting tangled up.

Regardless of all this; number one, YOU and you alone are responsible for your own safety. Therefore, each person has to decide where the greatest risk is and how best to mitigate it if they so choose. Personally, I prefer something that I know won't fail; as such, I have to be more careful in other areas (not putting hole in boat with hook and clearing hook if/when capsize occurs).