I used the pico-Palm with my MTR series rigs for several years. It works reliably.
For the past year I have been using a touch paddle with the circuitry built into the MTR3. It uses about 2ma of power so that’s inconsequential. There are many ways to make the touch piece. I cut away the shield of two RCA plugs and use the center posts,
The touch key has the following BIG advantages:
no moving parts so nothing can be damaged in transit
no contacts so they can not get dirty or corroded
much smaller overall profile so the rig fits in my shirt pocket (no pack needed for many hikes)
cheaper than almost any paddle
The two protruding touch points are visible to the bottom left in this photo. Note that I clip my log to the back of the radio, hold the radio in my left hand with the log, up, and send with my right hand.
P.S. the piece of blue foam shown to the right of the radio uses tiny magnets to stick to the face of the radio and protect the delicate switches during transit. The white dental case seen plugged into the antenna jack houses a broadband EFHW impedance transformer into which the antenna is plugged using no feedline. A tiny space-pen is tethered to the radio and transports in the pink soda straw seen taped to the blue foam. A 300 mAH LiPO velcroes to the top edge of the radio completing the set-up which weighs about 8 oz complete.