</font><font color="blue" class="small">( fittings with the solder already "inside" )</font>
No experience at all, therefore, no valid opinion, but I'd be a little reluctant to use them since I've always had good luck the old way.
Incidentally, for over 10 years, I had a Spitfire propane torch, made to go on the little one pound bottles, but I had an adapter, 10' hose, and used a 20 pound bottle. The manufacturer claimed you could solder joints with water in the pipe with it, because it got so hot, and they were right. That's one reason I never used the bread method because a little water dripping never kept it from sealing good. With that torch, you simply applied the heat 5 seconds and then applied the solder. And when that torch finally broke, I was never able to find another one like it; had to go with a Weller. The Weller was actually quite satisfactory, but just not up to the Spitfire quality.