is this one year i should be concerned about.
Yes, it is. If you look back at some older 18 posts you'll find various with this "best/avoidable" year discussion.
with the 18 dagger boards i was wondering would this be a big problem?
No, not anymore than it will be on an ocean when beaching, you need to be aware of water depths and when in doubt pull them up. There is a bungee system that puts forward pressure on the daggerboards to hold them in about any depth position you choose.
with the same skilled sailor could a 16 beat an 18?
You releaize you asked this question on the 18 page of 18 sailors. Seriously, the 18 is about 3 to 4 mph faster than a 16.
Looking at any older Hobie check the hulls for soft spots buy pressing in on decks and sides with both palms, the 16 in particular in front of the crossbar on the deck, the '83 thru '88 18 all around the front crossbar. There are older boats in good shape out there, and more that need work.
If I were really intrigued by the wings (which are extremely comfortable) but had the money for a newer boat I'd look for an '89 or newer 18 and look for the Wings in the classifieds. I'm not trying to talk you out of the '84 Magnum, but read some more on the hull reinforcement issue and look this boat over thouroughly.
Hey, the 16 is a nice boat too, but the 18 is a Mercedes!