Here is my advice and reasoning from a guy who actually went through re-hardening and using those blades for years after. To start, yes it was worth it at the time. But I first used the sebenza and made sure it was the knife for me in every other respect. After use is when I discovered I'd like a harder blade. Many people here would say it isn't worth the time. But when you find a folder with the tolerances, action, lock up, smoothness and simplicity of the seb but the blade is a little soft... you look for solutions. What other knife has the tolerances or action at the same price? As a lefty, the options were even smaller maybe non existent.
So I searched out Paul Bos and for the cost of 17 bucks I had a much better performing blade. After spending 350 on a knife, 17 bucks isn't too overwhelming. However getting it re-stonewashed of course adds cost, I just did my own refinish. I don't own the knives any more as I have insingos now (re-hardened blades were drops). I disclosed the changes to the buyers and lost about 60 per knife, not bad at all.
Having said all that, the new sebenzas heat treat is nice. Buy one, use it for a while and go through some sharpenings. If it is YOUR knife and the ht is still too soft you could send it out to Bos (Paul Farner now runs day to day). But then if you don't like the knife you can sell it stock before modifying it and not loose a bunch on it. That is my advice, but I don't think you need to modify the newer blades at all.