A friend of mine bought a 120 Tiger ARF and yeh buddy, that thing took some lead to balance. But what a sweet plane. He did break one of the landing gear blocks on a landing that wasn't perfect, shall we say, but by no means what you would consider a gear buster.

I use lead shot and epoxy. I like the shot . I can measure the amount needed very accurately. I like to pour the epoxy into a cormer, hardwood or even balsa ( if its not too much lead) and then pour in the lead. IF you are worried about the wieght coming loose, you can give the wood some tooth by partially drilling tiny holes in it.