Tim,
I have not speared in years but wanted to give it a try this season. I've never made a decoy before but my neighbor has and he gave a lot of pointers about weighting and balancing.
I also spent some time watching the judges swim decoys last year at the Westlake show in Ohio and picked their brains on what works.
This one swims pretty nice with a slow wide circle and a good injured minnow twitch on the up take. I think your fin size and position will determine how your swim glide action is.
Best way to figure it out is to just knock one out and mess around with it. A lot like tweeking a deke to get it balanced and self righting.
Have some fun,
Ballard