Hi Brett;
I have never tried drill rod, have never had the need. I have always had good results with music wire, but I have the ability and knowledge to do it correctly. I can get music wire at the hobby shop, drill rod has to be ordered. I don't know of anywhere in my area where I can get drill rod over the counter. I have no doubt that it can be very useful for our control horns, and again if one is careful with the torch, you can control the temps and keep the rod at the stage you want. But even that takes practice. Your average Joe bell crank doing it for the first time should experiment and test a couple of samples first. The critical thing with whatever one uses is getting the material too hot, which oxidizes things and makes them brittle, or not hot enough and you get a weak, cold solder joint. If you do it enough, you can recognize the subtle little differences. If you aren't comfortable with doing it and fear risking your latest world beater, front row machine, better get something from one of the vendors. Otherwise, practice, practice practice and test, test,test. Doing one or two joints might not tell you everything you need to know, which ever material you are using.
HAPPY HOLIDAYS!
Dan McEntee