hydraulics
2 things. If you find a self contained BS cylinder at a great price, I agree. If you found a panel mount system with ability to add the hyd vang in the future, then I would go hydraulic vang at some time..
I REALLY like the solid vangs(hydraulic or not) for the support of the boom and elimination of the T.L.
However...if you decide to stay with a purchase system vang, here are some thoughts:
1). One good way to deal with the TL is to have a snap shackle on the end as you say. Rig a bungee cord from say, the mast collar with a loop on the end-adjusted so that you can bring the TL forward once the main is up and clip it to the bungee. This will hold it in place, out of the way so it won't beat up your new main sail leech, and still be easy to get at-
2). A variation on this is to have a bungee on the backstay toggle, and clip the TL there-this will hold the TL in tension, just parallel the BS, and also out of the way. You can still keep some extra line on the TL-with it cleated in the normal boom height for non-sailing time, yet have the ability to raise or lower the boom for those times you may want to:cockpit parties, furling the main with short people, etc.
As for purchase, 3:1 is in no way enough to do anything, and actually the lack of leverage in the mid boom sheeting is precisely why a powerful vang will help immensely. By using a strong vang properly, you will find the loads on the mainsheet are less and it will be much easier to work-let the vang take a chunk of the load-but to do this you need a good one. An easy way is to start with a 4:1 or better, 6:1. Then add a doubler-instead of attaching the vang to the tang on the boom, attach that end of the vang to a piece of wire or high load line, and run it through a block mounted on the boom tang, then down to wherever you have the vang anchored at that end-this will double the purchase you have in the block and tackle system, and at 8:1, or hopefully12:1, you now have a workable system. This can be arranged in several ways to achieve the same result, but hopefully you get the idea.
Whaddayathink?
S