I've used ROM Manager just fine with S-ON. I've rooted, loaded custom ROM images, and even replaced ROM Manager with TWRP without having S-OFF.
I do understand that flashing some images may require S-OFF, but so far I haven't run into any.
Incidentally, there's tons of info out there about how to switch off security... but how about turning it back on? It's my understanding that having it ON protects your system software configuration against catastrophic changes. After doing whatever is necessary with it OFF, I'd feel more comfortable switching it back on. Is that possible?
Using fastboot commands you can use the command
Code:
fastboot oem writesecureflag 3
That should make you s-on.
If you aren't familiar with fastboot you can use the guide in the first post to obtain all the drivers and software needed and how to get into fastboot.


) that since you're S-ON, you can relock, flash an older RUU with firmware (of course), then unlock again. A bit lengthy, but one of the costs of S-ON. That should get you back to where you were. I think! 