We run a braid program very similar to yours Gill-T, with very similar results is sounds like. The only exception is that we use 30 lb Power Pro (dark green). What I like about this is that I can run either a dipsy or a slide diver on it, and for both salmon/trout on the Big O, and when I need to get deeper for the walleye on Erie in mid to late summer. I'm brand new to downrigger fishing though, so I won't comment on using braid on the riggers.
I definitely change leader lengths and weights depending on whether its a dipsy or slide diver, and whether we are chasing Kings/Steelies or 'eyes. For spring Kings/Steelies we run 20 lb leaders, in the fall we bump it up to 25 lb. For the eyes you can go as light as you think you need to. I typically run about a 12-15 lb flouro leader though.