I'm obviously a tightwad. My preferred power connectors are Deans (T style) and I use 12.7 mm heatshrink. If the wires are a bit thin a few slivers of hot glue into the back of the connector before applying the heat gun fix that. 12.7 mm heatshrink is just big enough to fit over the body of a Deans connector.
12.7 mm is the diameter before shrinking just so there's no confusion. In my opinion, since the heatshrink is snug around the body of each connector half, it provides good strain relief when 'pulling the plug'.
I can see the attraction of the MPX green connectors for that big glider I keep building in my dreams though.