Practice flying without your canopy. It's not hard to do at all.

You will appreciate the practice time WHEN your magnetic canopy comes-off in flight.

IMHO, it's a poor design...period. There have been many thousands of succesful flights using magnetic canopies, but I have never seen a properly built and installed conventional canopy come clean off, while I have seen MANY magnetic canopy failures. They fail in every type of aircraft, every type of flying style and every size. In order to get adequate holding power, you would need almost 100 times the weight of a simple blind-nut and 4-40.

It's just a bad idea, no matter how 'clean' it looks on the ground.