All the 753 blades I have measured were just as thick as 531. So even in the worst case where you lost the heat-treat, they'd be as strong as 531, which are if anything a bit too strong for my taste, for most riders and purposes.
I really wish they'd made a lighter blade, to make proper use of the stronger steel, if only to get a more supple, bump-eating "undamped suspension". And maybe they did, but again all I saw were the heavy ones. Even Columbus SL were a little lighter than 753 IIRC.
Plus you can put brake bosses on with silver, if you make a suitable fillet. Fillet Pro from Cycle Design is probably the best filler rod to use, though any old 40% silver is probably good enough if done properly. Yes 40% has a liquidus a little hotter than Reynolds recommended for 753, but still way cooler than brass, and with fillet brazing you're working above the solidus but below the liquidus — in theory anyway.
Mark B