Never spent much time with a line counter, so I'll give my typical naive ideas. I imagine that putting much resistance after a high quality reel could give you some backlashing issues. Not an issue if you have the bait clicker engaged. You couldn't cast with them obviously, but wonder if there is anything to worry about happening such as a snag causing a backlash and then breaking you off before you can get the boat stopped? What are the biggest problems with the clip on line counters other than quality/performance? Sounds like a pretty good idea to me, as I'd probably rather buy one of these than a rod and reel trolling set-up.