Jim.My success rate was about 85%. The ones that failed would do so quickly. I expect that your method would be more reliable.
The reason carbide-on-steel brazing sometimes fails is due to different thermal expansions of the two materials. Even with a perfectly brazed joint, sometimes a slight tap on the carbide bit can cause it to snap. The trick is to use a special solder sheet where a thin (0.005) layer of pure copper is sandwiched between two layers of a copper/silver/manganese solder. The copper layer will take up the tension caused by the different expansion rate between steel and tungsten and form an extremely strong bond.