Mark and Lisa make a good point, that a proper crimp is easier to accomplish than a proper solder joint. By proper crimp I am talking about a four lobe crimp on a tubular wire receiver using a M22520 ratcheting crimper ($200 - $500) NOT a "B" crimp on a stamped contact using a $20 pliers type crimper.  If you must use a connector, using  MIL spec pins and crimper are the safest options. If you need to make a connection that will remain connected for most of the life of the airframe then solder and heat shrink will yield the lightest, cheapest, and reliable connection.

The ability to suspend a 5 Lb. weight, while entertaining, has little relevance in the evaluation of the suitability of a connector system.  Static loads don't fail connectors. Corrosion, thermal cycling and vibration (with its friends fatigue and fretting) are the long term culprits. The very design of the Fast-On invites moisture to come and stay a while. 

If Fast-Ons were such a great value, wouldn't you see them in late model cars or avionics?

Having stirred the connector pot, how about this:

The only wire you should use (except coax or proprietary cables) is MIL 22759 (single wire) or MIL 27500 (shielded) and you should only use thermal strippers (hot blade) to strip the insulation. Never use PVC insulated wires, including wire that may be included as part of some products,  and never use sharp edge strippers.  PVC has a lower melting point than Tefzel (used in the MIL wire) and sharp edge strippers often nick the wire's conductor strands. These nicks form stress concentrations that, with vibration and the copper's work hardening, lead to mechanical failure of the conductor.

Reliability is a product , in part, of attention to detail.

Regards
Brent Regan