MT,
For me the flat bottom puck is far easier to attach and remove. Have been using a Vexilar LC-10 with that style transducer for years. Mounting the transducer below the thwart directly in front of stern seat. Day 1, small dab of silicone on bottom of puck, press it down and it's good for the trip. Last Day, break out the 99 cent click knife and scrape/slice it off. That point of the boat suites the puck style better.

Nanda,
Still don't understand how i missed it the first couple times i looked for it. one of those duh moments, and already had the question posted here. Happy fishing to you too! Without the depth finder, we're feeling around in a dimly lit room.
Tim