My masthead Windex arms are set 55 degrees apart. Down wind I use this as my gybing angle for most wind conditions. However if the spinnaker trimmer is having a problem with lack of pressure on the sail, I will sail a bit higher to get the breeze flowing back in the spinnaker. Like wise, if I feel a puff coming through I'll bear off with is and run a deeper angle. I am a firm believer in the KISS principle on boats.
Less gadgets means less breakdowns.
If you have a sheave box above the fore stay there is a good chance you will break your mast at that point. I have already mentioned a couple of times the need to position the crew weight out on the rail to keep the boat flat. I think a lower life line is a good idea so that the crew can put their heads out under the upper life line legally. This is better for getting more weight outboard, plus is more comfortable. The crew weight should also be kept together.