I have yet to paddle them back to back (my Magnet is out on loan).
From my recollection I expect the Storm Chaser to track better and be slightly faster while also pivoting quicker.
I expect the Magnet will be a little easier for a beginner to paddle (not that the Storm Chaser is hard).
The biggest difference as far as this thread is concerned is you can find a Magnet used... you are very unlikely to find a used Storm Chaser at this point! Since Gary specifically asked about the mold and new ones being available it was nice to see Class V post.