A bit late to this, but felt like sharing my knowledge here for anyone else who may visit this thread for help, it is possible to "unlock" (not sure if it means S-OFF but I seem to be able to edit everything I need to even though the toolkit says it's not S-OFF) the bootloader and install a custom recovery on the new HBOOT (mine's 1.27, not sure if that matters either, but it's the T-Mobile OTA one).
First, use the HTC Sensation 4G All-In-One Toolkit
to unlock your bootloader (use the HTC Dev way) and install CWM or TWRP.
After that, go to androidsu.com
to download the latest superuser and place it at the root of your SD Card.
Then, boot into CWM (or TWRP) and install the zip.
Congrats! If everything went as it should, you should be rooted, you can then install the recovery of your choice and do whatever you want with the phone.
Turns out that my HBOOT was S-OFF after all, I guess it carried over with the update. However, all hope is not lost for I have found an S-OFF guide for the new HBOOT here
if you are still trying to S-OFF. I haven't tried it myself, since I found out mine was still S-OFF.
Edited by Refresh100, 04 June 2012 - 12:37 PM.