I have a pair of convertible pants from Campmor bought several years ago. I bought them because I had planned a couple of trips with a lot of stream fording and thought it would be useful to zip off the legs. However, several experiences changed my mind:

(1) At the fourth ford, I tripped and fell in. Even though it was drizzly, cool weather, my pants and shirt were dry after 15 minutes of hiking. In fact, by the time I emptied out my pack, dumped the water out of the bottom, checked my sleeping bag and puffy jacket and repacked, they were over half dry. After that incident, I stopped zipping off the lower pant legs for stream crossings. (BTW, that's why your critical insulating gear should always be inside a waterproof pack liner or in dry bags--stuff sacks or a pack cover wouldn't have kept the water out.)

(2) I never hike in shorts. I'm allergic to sunscreen so need to keep covered up. I also prefer not to show off my varicose veins and large scars from my knee surgery. However, my main desire is not vanity but to avoid exposing my already sun-damaged skin to further damage. If it doesn't matter that my lower legs get wet in stream crossings, why bother with shorts?

(3) The convertibles weigh almost 6 oz. more than my regular supplex hiking pants, almost double the weight. You might want to do a weight comparison of pants plus lightweight nylon gym shorts (a more versatile combo) vs. convertibles.

YMMV, of course!