Thanks, everyone, for the kind words and the warm welcome.
For those unfamiliar with fillet brazing (though I'm certainly no expert): Unlike Tungsten Inert Gas arc-welding, which actually melts the tube material at around 2000 degrees F. in order to fuse the tubes together, brazing uses brass (or occasionally silver) - which has a lower melting point than the steel tubes - as a metal filler to 'glue' the tubes together.
The tubes are heated to the melting point of the brass filler (1600 degrees F.) and the brass flows onto the tubing, diffusing into the steel to form a metallurgical bond. The same process is called soldering when working with low temperature fillers like lead or tin.
A fillet brazed frame will be around 4 oz. heavier than a welded one but, IME, they tend to be damn strong, even with stupid-thin steel.
Before filing and sanding (a critical stage; any filing mistakes can create stress risers in the steel tube):
Bead-blasted and clear-coated: