Good post, Dave. I have used the condom method, as shown, since I started vaping. Very easy. I also add a step of taking off the rubber mouthpiece, as I've created a few geysers if I press the carto down too rapidly. Juice comes shooting out the top. In addition to filling from the condom, I'll also pour more juice into the top of the carto. I then pull the condom out a touch and squeeze it a few times. This flushes the juice up and through the carto. I then remove the condom and gently blow out the excess back into the condom. The excess juice goes back into the condom, and it's already prepped for the next refill. I do a quick blow into a paper towel to remove any juice caught in the central tube, wipe the outside, and fit onto the battery.
I am thinking about giving syringe filling a try, as I get a free one with every Crystal Clear Vaping order.