Will,
To be honest whichever boat you plump for your gonna have fun. My opinion is you will probably get more boat for your money with a H16, plus you are more likely to find second hand spare parts for a H16, which could be an issue if you are on a budget. After all alot of new parts are probably going to cost you about the same as you payed for the whole boat.
The Nacra is going to give you better performance and will be more forgiving, but unless you are racing its probably not an issue, and if you are racing then its far more important to go for a boat that your buddies are sailing. Bottom line if you want to have a faster boat go for Nacra, if you want to be a faster sailor go for a H16 (if your buddies sail a H16).
The difference in speed is probably not going to be much faster that you can crawl. So you are not going to notice it unless you are sailing boat on boat.
Be sure and let us know what you go for.
If you like the look of the Hobie more (and perhaps more importantly in your case if the girls like the look more) don't let people push you to go for something else.
Be happy with what you buy.
All the best
Gareth
www.fourhulls.com