I have scotty mounts on both rails and have not had any issues what so ever. I like the convenience of being able to grab the rod quicker when a strike is on. With that said, I never have the drag set to tight...not because I think the boat would tip or the handle would break, rather...I was always taught that you should have the drag....just tight enough for line to get pulled with just the right amount of pressure.
I agree with Tom, unless you are attaching a Marlin rig onto your bars with the drag set at 100%, there is a chance that the mighty marlin's strength and speed in addition to the strength of the line might snap the bar off the boat. However, if your drag is set right...you would have ample time to pick up the rod and fight the fish.
2006 Wildy Ride 135