Bzdura, nowe HBOOT'y maja zabezpieczenie przed zapisem i nawet jak odpalisz RUU (bez downgradera) S-OFF zostanie.
Will my phone stay S-OFF forever?
Yes and no. As soon as you decide to flash a stock RUU that has a HBOOT update in it, this hacked HBOOT will be overwritten.
You do have the option to remove the HBOOT update from the rom.zip inside the RUU. Since your phone no longer checks signatures, you could easily do that.
Also, you then still have the option to flash custom recovery, or different kernels using the fastboot functions described above (fastboot flash, et al).
To jest info ze strony alpharev.