http://www.gregorie.org/freeflight/s...soldering.html :
The idea with wire to wire joints is that the (copper) binding wire provides the strength while the solder merely forms a matrix that locks everything together. The binding should be tight before you solder that join. If you can only see the solder and not the binding, theres too much solder on the joint; the ideal is that just enough solder to wet everything involved in the joint is used.
I personally do not thrust joint without wire in high vibration (all glow airplanes) conditions.