I can't speak for or against the Nacra but I have owned a Hobie 16 for 20 years and sail both lakes and ocean. I don't care for racing. When I started looking for a used Hobie (I ended up buying a new one) I also looked for a Nacra. I was told that they are lighter and faster but the hull construction was thin and vulnerable to damage. There are many more H-16 out there so you have a better chance of finding a good used one. After 20 years I am amazed at how well mine has held up. I pitchpoled twice in that 20 years and it was my fault. I have no trouble coming about, just backwind the jib. I set the boat up alone and sail solo much of the time yet I have sailed with four of us with no problem.
I believe the Hobie 18 compares more to the Nacra since they both use dagger boards and rounded hulls. The 18 is more of a racing machine. The dagger boards and jib blocks which are in the tramp reduce the effective size of the tramp. I believe the 16 has more room to move around.
Any catamaran will be a wet boat but the Hobie isn't bad. The wettest boat I was on is an Isotope. It is a very fast boat but very low.
Howard