Welcome to the forum Woodchick.
I don't own a 505, but I do own a Legacy 3300 which is the same as the Discovery 3300. I also own a Land Star.
Now both the 3300 and the Land Star are good coin magnets, both have good depth. The Land Star is similar to the 505 so it does not have the digital display with the numbers like the 2200 or 3300.
The Land Star works really well on the beach on dry or wet sand, you have to ground balance it for the wet sand area's.
The 3300 is a great detector on the beach in the dry sand, I've not had any luck with wet sand yet as I've not long had the unit (2 weeks) so I am still playing with the settings on it.
Out of the two, I like the 3300 due to the digital display with the numbers on the screen, it gives me an idea of what the unit is detecting with more accuracy, it's also a tad lighter than the Land Star. I just recently found some sun glasses in great condition at a beach local to me (Oakley sun glasses .. $275.00 !!), the 3300 detected them at a depth of 8"in dry sand, it was on the button with that. Both the 3300 / Land Star will detect a quarter at 8+ inches and a dime at 9 inches. I've also detected soda / beer cans at over 2 feet deep. The Land Star is a ring pull / tab sniffer, it will see a ring pull / tab at 7+ inches (rings of the gold kind come in this range along with nickles).
The Legacy 3300 is $249.00 new and the Discovery 3300 is $299.00.
The Land Star is around the $350.00 mark.
I hope this helps you out, and good luck with which ever one you decide to purchase, and happy hunting.