Nick,
I added a spin to my 18 for the last year or so that I raced it. I've got a bunch of pictures and can show you what I did.

Also, if you're interested - I've still got the spin rig including sail that I put together. When I sold the boat it was going to a lake and the new owner figured he'd run out of real estate too quickly with the spin up. So, I've got a H-18 SX spinnaker (great condition), fiberglass pole, some lines and blocks and a bunch of pictures. The stuff is mostly collecting dust in my large collection of boat bits, so if you're interested we can make a deal. Since I'm in the Annapolis area you could come see the bits I've got.

The 18 with a spinnaker was a blast. I haven't sailed a spin boat since and I kind of miss the addictive feeling of a cat heated up with a spin...

I can't say much about whether a hooter would be better, but I can say that the spin let me sail deep and fast, and since the 18 is a great reaching boat I didn't miss the ability to carry the headsail higher (unless the wind was really light).

The Mighty GBH (Geriatric Blue Hobie) under spin in Galesville Harbor, light conditions:



West River, flying a hull and trapped, smokin'!