[HTC One S] Sneakyghost:
After having had two terrible days with my device nearly bricked from trying to find a fix for this horrible issue i can now report being back online.

Plus, i have used MiniTool Partition Wizard to zero out the SD Partition on the phone and then re-run the RUU 2.31 and then installed viper again and after that, the phone acts a lot more snappy and the Home Button Issue has pretty much changed to "Locked Capacitive Button" issue with hardly any occurrences of the actual home screen switching.

This behavior is known as the newer symptoms beginning with Base 2.21 and being stronger on 2.31 and 2.38. So, it's not fixed at all but way harder to notice. :D

Might goof some into believing they had a fix there. Just mentioning ;)

People, if you ever have difficulties on the One S with the SD not mounting properly after messing too much, i can only recommend doing a thorough wipe with nulling all bits using some tool like the above. I knew i had to go this route because i had similar experiences on the HD2 already. This is sometimes truly doing wonders. Fragmented data leftovers on the SD partition does not go well with an Android system for some odd reason. Doing that once in a while together with a Factory Reset and a RUU this keeps the device being a nice toy.

It doesn't fix the Home Button issue though. Just maybe a helpful tip for all the messies out there.

[EDIT]

I did the phone of my wife today and also lost the USB Mount and also Android internal mount of SD Card. I could not get it back by formatting and nulling the Card this time. I am kind of stuck, tried pretty much all known and recommended procedures but the EMMC Partition won't mount as USB anymore, only if USB debugging is switched off. So it's some sort of Semi-SD brick which is killing me right now. Will report back once i get some idea. But might have to send it in eventually.

[EDIT 2]

The SD Semi-Brick was most likely caused by using TWRP and the formatting tool i linked above.

I could finally fix the Problem by clearing Storage with the stock recovery and factory resetting, then flashing CWM and then installing a ROM. It would then still complain and make me format the SD in Android. I then ended up with the SD mounting in Android and in CWM as well as USB storage but as soon as i enabled USB Debugging, the USB mount would be lost. That is not normal, usually both go well in parallel. So i checked again with MiniTool and found out that the SD had no drive letter assigned to it when USB debugging was enabled yet it was visible to the partition tool. So i assigned a drive letter, went back to bootloader, cleared storage again, wiped the card, reinstalled the ROM and then i had the card back.

Just for testing purposes i installed TWRP again only to be quite sure and i was right: The Card lost its mount again, but since i didn't mess with MiniTool or EASUS again a simple clear storage in hboot would now suffice to bring it back.

So, to conclude, nulling the SD is still a very good idea, especially since it seems to have fixed my Home Button Issue for the time being (very very clean install of 2.31 RUU afterwards) but it is a very dangerous thing to do at the same time if one has to go about it like me: knowing nothing about Partitions, MBR's, Mount Points and the like.

I am just very glad i could bring it back to life by use of my instincts...