I'm 0 for 3 so far. I noticed a color change in two melons, checked for slip (didn't pull off) and let them sit a day more. The next day they were quite orange (on the outside) and little beetles were congregating on them. So in they came, finally slipping from the vine. Both were over ripe, although still very tasty, way juicy, flesh almost translucent, like the deep green part of a honeydew when it's getting over ripe (but orange, of course). Never seen a cantaloupe look like that before.

I brought in a third one today when it was looking just a little yellow. Had to really tug to get it loose. Same deal, seems way over ripe and this one has that sharp musky flavor that's not too nice (although still quite sweet and way juicy and translucent).

So I give up! How do you know when they are ripe? I have a few more less mature ones coming down the line.