Why I like a full keel
Sad story-about a month ago a fellow that lived aboard his Endeavor on the Merrimac disappeared and is thought to have drowned. His dog was found tied to a tree, his dingy swamped and his cell phone on the cabin table. Extensive search of the river found no body. I'd spoken to him weeks before about his cruising dreams. Went to look at his boat hauled in a parking lot and observed the mooring line wrapped around his prop. I could imagine him leaning out of his dink trying to disentangle the line from his prop and falling in. Current is too fast to swim against and the water too cold to survive.
For all the extra speed and pointing ability you get with a deep fin, I'd not trade it for the security of a protected prop in an aperture.