Hmmm.... I use the "can't miss- style" handle. They are very popular among sailors. Most actively sailed boats in my area use this style.
I also use a spreader bar - but not the stuff that Murrey sells. I use one that is designed for windsurfing. Most of those do not have pointy hooks - less of a risk to cause damage to gel coat and tramp.
I have used the keyhole style system - It is nice and works well. I do not own it because it is expensive.
I have not used the quick release system - It looks like a nice system for lots of $$$'s. In the future this might be a requirement if you sail in a competitive way. Research the Hobie class rules - IIRC there is something about the need for a quick release between harness and wire.
Harness... check those out http://www.justsail.com/magic_marine_harnesses.htm If I would decide to get a new harness I would get the "smart harness"
Safety... In a capsize situation you will be able to unhook. I would be more concerned about pitch poling situations where you might get tightly wrapped around a shroud or the other trap wire. The bad news is that the quick release might not fix that problem depending where or what is tangled up.

Patrick