the main comparison between the 5.2 and the h16 is that they both have 2 hulls. they are very different boats.
The TheMightyHobie18 compares to a 5.2 because of the daggerboards, but the TheMightyHobie18 boards are more user friendly.
old 5.2s have a bar that runs fore and aft down the center-a real genius idea...not
In some areas of the country an old H16 is free or close to it. that's an incentive in my book.
as written above, how & where you will be sailing is your main criteria for this decision.
i believe pitchpoling a Hobie is pilot error and can be avoided although i think it is harder to pitch a 5.2. Also the raised deck of the H16 does make the boat easier to drive in heavy conditions as the sailors get hit by less sheets of water.
i would think parts costs would be similar in all the old beach cats. More chance of finding used hobie parts though. the hobie castings are expensive, but nacras don't have many castings. Hobie rudder systems are more user friendly as long as they are maintained. the use of a piece of line to operate your rudders is frought with difficulty. not a fan of the rope-a-dope style of rudder up down.