I replaced my other boats (pluriform) by a single F16 that does all and many years on I'm as happy with my choice as I was in the beginning. But that is me.

If I were you I would either sell the stuff you have now and replace it with a single craft that allows you to do both (2-up and 1-up) or find a very nice second hand Nacra 5.0 (Not many second hand Nacra 500 around in the US yet I fear).

I can't live without the spinnaker and I assume you are no different in that respect. This means the H16 is out. With regard to other second hand boats, I'm not sure they are worth spending the cost of a spi package on.

With regard to the H17, I found that boat to be a B^%$# to tack and gybe. The boom is really waaaaay too low on that boat. Not something you want when gybing under spinnaker. I'm 6 ft 2 inches and weight 190 lbs.

Wouter