I have quite a number of units that use them or are going to use them. They make an interesting size unit with basically double the runtime of a 10440. I like to have extra cells of just about anything I may build. Nothing over 26650 for me so far. Also use lots of 10440/14500 in LiFEPo4 for 3.2/3.7 full charge builds where 4.2V or doubled 8.4V is pushing it. Lately I've used them for LPC826 builds with a $3 aixiz driver where I turn the pot past the stop and 2 10440s would end up over driving the diode and blow them. With a LiFEPo4 it's driven on the edge and hit just over 400mW with a G2 although I just use the acrylic and still get well over 300 (more like 320-350). Lots of Altoid box kind of builds and 1 pen so far. What other $6 diode can do that?
You can also get a $3.50 bluray diode and use the same driver to get 150mW of 405nm
After all that I would say that the 14500 isnt used as often as the other sizes just like 18490/500.