I've fixed a few such electrical nightmares over the years. The style of butt connector you've chosen is pretty good for those who don't have a soldering iron, or the area is just to tight to work in with an iron. I still prefer to solder any connections like that, myself. Well worth the time it takes to get rid of those splice/taps though, they're just a nightmare when it comes to trying to figure out electrical ghosts. One second they jiggle together, and everything works, and the next, you've got lights blinking on and off, and things that won't function properly if at all.