I got a Penn 625 downrigger and have a 6 pound ball. It needs new cable but I cant get any right now. I have 80 pound power pro sitting here but Im not sure if its strong enough to hold the weight? Trolling will be under about 6-7 knts
it will work fine,this tournament season we started out using200# tuff line then we stepped down to 100# power pro with 10# balls on both so with 80# braid and #6 balls, you will be fine
the power pro has far less resistance going through the water than mono and wireand no humm like wire. many of the tournament anglers have been having problems using mono on their spools, mono will swell with temp changes and salt residue and has been splitting the spools. Cannon came out with the new white downriggers with the stainless spools this year specifically because of the problems with mono
your biggest problem is going to be trying to use them at 5-7 kts. downriggers are not designed for trolling that fast and will rise considerably defeating the whole purpose for having them, at that speed, your better advised to use trolling weights (cigar shaped).
the biggest problem that can happen with braid is that they will wear and groove you rollers (at the end of the boom).
I tried 80lb spectra on a penn downrigger. Didn't really care for it. Tough to handle it broke once with a 10lb ball. I imagine you would be close to skipping a 6lb ball with all the blowback at 7knts.