Solder is only bad when it acts as the transition between a wire and something that is vibrating. Two wires that are soldered together, protected with heatshrink and bundled with other wires will be far more robust, reliable and lighter than ANY connector. This is especially true for trim motors, lights etc. mounted in the ailerons and empennage, where moisture, dirt, vibration all conspire to compromise a connector and where weight is critical as it must be counterbalanced.

This topic has been hashed over on the list periodically for the last 10 years (cripes, has it been THAT long...). Recommend you check the archives.

Regards
Brent Regan