We silver brazed contacts for locomotive braking switches and reversers daily for 20+ years before GE reorganized and closed the shop we dealt with. We were happiest with natural gas- oxygen. We had a "high pressure" gas line installed, but the 2 PSI was marginal for our torches, so we eventually went to propane. We were spending $300 / month for oxygen, so we got an oxygen generator that extracted it from air. I looked at getting a natural gas booster, but the market became so unreliable that we never got to that point. In the beginning, we just used a regular oxyacetylene welding outfit, but that required care to stay between the melting points of the silver solder and the silver contacts we were attaching to copper blocks and the acetylene cost was high. I used MECO torches until I got tired of being burned by the leaky joints catching fire, then changed to Smith and never looked back. I have a Prestolite torch with only one tip, but it is so wimpy that about all I use it for is heating vacuum lines to outgas them. I also have a Little Torch like Larry's, which is a really neat unit, the way to go for tiny work.
Remember that air is 4/5 nitrogen, which doesn't burn. A gas air torch is blowing one part heating flame and 4 parts cooling nitrogen on the part. About all I use a Bernzomatic torch for is soldering copper plumbing.
For low volume silver brazing, my vote goes to oxygen-propane and for welding and brass brazing, oxyacetylene.
Bill