We put ours about 4' up the mast. That way you can pull up the spin from a standing position - which seems to be quicker and easier than when on your knees.
We used a large Harken swivel cleat (140) for the halyard - as used on the Nacra Infusion. We still sometimes have a 5mm spin halyard pop out of the cleat under high loads - we think the swivel cleat frame is not stiff enough and the flexing under load opens up the jaws enough to let it slip.
Adding an extra section of cover to the halyard at this location helps prevent this happening. It also gives you a clear visual cue that the hoist is complete.
The cleat has to be removed from the frame and turned upside down so you pull down to uncleat - to make the take down easier. You also have to lose the eyestrap.
We run the halyard from the mast cleat to a block on the front cross beam (with a spring to hold it up), back to a turning block on a bungee on the tramp and then following the normal routing to the snuffer bag. This allows the halyard to be uncleated very easily during the take down. The crew holds the retrival end in one hand and gives a tug on the halyard between the cross beam and the turning block - which pulls the halyard out the cleat and lets the drop start. The crew can then get both hands on the retrival line very quickly
I can't recommend the ronstan cleat that Hobie put on the mast as stock - a couple of us blew them up very quickly when reaching with the kite (distance racing).