Bob Brown made some great observations about brazing 953 on his blog
HERE and
HERE. Temperature contol using the torch is much more critical with stainless than with chromoly or manganese molybdenum, or as Bob says, "Stainless is very different to braze because it behaves the same as regular steel during the heat-up phase, but once it's up to temp it can overheat instantly if you're not careful. There's far less margin of error than with regular steel."
I'm building my second lugged chromoly frame and won't attempt building a 953 frame until I've built several more chromoly frames and get better at handling the torch to regulate the working temperature.