I have been using the amp connectors for the last two years with no problems.I also use some molex and have never had a problem with the pins falling out. I don't use the molex exposed outside, but I know others that do and other than possible problems after a rain have been happy with the results.
Here is a picture of a 15 channel junction box for my leaping arches. I have an 18 conductor cable that I bring from the controller to this box. I tape up the wires to prevent too much moisture from getting in the connections. I have had some water accumulated inside the box, but never enough to cause any problems. There are 3 shared neutral wires one for each set of 5 channels. Each channel only has a single 100 ct mini string. They sit on the ground all season and have never had a problem with them tripping the GFI.
I love the amp product, but they do get expensive compared to a molex connector. They have a twist lock design so the do not pull apart. There is a gasket, but I can't say it does much. I get them from Mouser, but always looks for a better deal.
The second picture is of the bottom of the controller box where the 15 channels come out.