I have several friends with proboats, and all the rudders are the same, different size or course, and I have yet to see a problem with them. I do see where there could possibly be an issue with the rudders, they are simply tack welded. All the other radio equip, push rods, throttle cable ect is apples to apples in both boats. The two high torque Servos in the 55 seemed hoaky to me, but they work just as well as the 1/4 scale in the Manta.
The radio box in the 55 is SOLID as a rock, it is all fiberglass, I have no clue where you guys say it flexes, My Manta Rays radio box flexes, it is Plastic, but not the BJ 55's radio box. I believe we all agree that Warehouse Hobby's puts out a great product, so when I got home last night I broke out the tools and the put my BJ 55 and my Manta Ray on the work bench and COMPLETELY DISASSEMBLED them for a side by side. After reading all the posts on the forum, and the different threads about the BJ 55 I wanted to get a better look at my boat.