I did not read all of this thread, so I do not know if this was mention.

Don't change the spd...change the cleat. They make a muti-direction release cleat that I have been using for 5 years. You do not have to twist your heel. Any way you pull it will release, and it do not come out unless you want it to.

It is a 20 dollar item and it changed my life.

trust me and give it a try.