Jim, I haven't found my boat top heavy, mainly because the hull is very solid. The sides, bow, transom and cross members are all 12mm pine, and the bottom is 6mm plywood. I told the boys in our club if it was no good as a boat we could use it as a step :) The superstructure is 1.5mm ply, and the battery is a 6v 10ah SLA. The motors are 550s with built in fans, and the 2 speed controllers are Mtroniks Viper 15s with a BEC, so I don't use Rx batteries. It floats right on the waterline, and wind did not seem to affect it - perhaps the fact it is bigger than the plan helps in that regard.
Martin, I need 1/16" brass rod and will get some on my next visit to Lismore. I ran out at the crucial time, and our local hobby supplier did not have any. I have many other sizes in my stock collection, but no 1/16".
Peter.