I think we all get hung up now and then but kokanee fishing usually targets fish suspended over deep water. If you're fishing for other species like Macs, I get your concern.
I run steel cable exactly what comes from the downrigger manufacturer. Used to run Cannon's but switched to Scotty's. When I have gotten myself hung up on the bottom, the Scotty's brake adjustment always saves the day. Once I realize that the DR is paying out more cable, I reverse or turn the boat and head back to the snag. Yeah, your trolling rigs get all tangled and you have to deal with that but it's better than dropping the $35 DR ball into Davy's Locker. I believe that most DR manufacturers recommend having a good pair of dikes onboard for such an instant but I've found that quick response and a good brake adjustment on the DR itself has helped tremendously. Check your owner's manual for proper brake adjustment.
If you're looking to insulate your DR ball from electrical charges, Scotty makes a plastic snap that goes between the cable terminal and the ball. That's a whole discussion on it's own if you believe in the electrolisis theory and it's affect on fish attracting/repelling. I've read about it, measured the voltage to the DR cable (yeah it's measureable) and even tried to minimize the excessive voltage but I still put lotsa fish in the boat.
So, I'm right back to the DR brake system. Make sure your's is set correctly.