I like to make the best out of what I have and if a little extra time in rewiring these fixtures makes them more bullet proof then so be it. I am planning on running 12 awg wire to these fixtures and trying to find out if running that 12 awg wire inside the box is the way to go.
If the wires easily disconnect then you would be better off with no external connections. But with that said you would probably be fine with just hooking them up to the existing wires. I don't have LED lights, but whenever I wire anything I try and keep as may connections out of the weather as possible.