... I spent hours and hours with all sorts of schemes to try to make them reliable.
I did too, and I understand exactly.
I can't explain it, but after I moved to this QTH --with the TX antenna about 250' from the shack and the coax feeding it buried-- something changed. They weren't so touchy after that.
Having said that, the weaker RF field may have had nothing at all to do with it. I can't explain what else I may have done to make me like those capacitive paddles, but I may have also readjusted them.
I didn't change to the Bencher iambic for the same reasons you did.
1. 60/40 solder cold flows, and I was always afraid that the spring contacts (under constant tension with the paddles in) would eventually come loose from the PCB.
2. With the Bencher to the right of the keyer, the paddles don't stick out. They used to be in the way unless I was operating CW.
3. I just wanted to try a Bencher, after having made an iambic key years ago that I didn't like the feel of.