Re: manual jack plates?
The Bob's has a lot of adjustability. All kinds of combinations to allow for all kinds of fine tuning the set up. Nothing wrong with a TH. There are several that have a single center screw for adjustment. We've sold & used many different ones. There's one thing I've learned -- nothing beats the button....
Seriously, I don't think you can go wrong with a Bob's, TH, CMC, Vance and others. It's simply a matter of personal preferance. I'm guessing one of the lightest ones would be a Bob's. And with a 70 you may not need the 6" setback, you can always bolt it up at 3".