OK, odd questions, someone else linked this, but some of what's being described sounds slightly familiar.
Those who suffered eMMC failures:
1) Was it a total failure, or were only some parts of memory dead?
2) If it was just part of the chip, which regions were toast?
3) If it was just part of the chip, did it occur after doing a wipe/format of the affected region? What method to wipe/format was used? (Note, flashing firmwares in recovery usually does a wipe/format cycle).
The reason I'm asking it is:
Most of the reports indicate M4GD2E chips are "bad", SEM04G chips are "good".
M4GD2E looks like a Samsung flash part number. (Samsung does sell flash chips to many other companies, including but not limited to Acer and Amazon, and if HTC devices have M4GD2E eMMC chips, that's probably Samsung flash.)
Those of you who follow Samsung devices are probably aware of the "Superbrick" phenomenon in those devices. (Which also has been confirmed to affect the Acer A700 and some Amazon Kindle Fire units, due to using Samsung eMMC chips.) On affected devices, it happens when MMC secure erase commands are fired at the chip (and, also, is not guaranteed to happen when a secure erase is issued). This most commonly happens when using newer CWM recoveries (CWM 5.8.x and 6.0.x for sure, possibly 5.5.x, I can't remember if that was pre-ICS or not.) that were built from an ICS or newer source tree. Note that there are numerous cases where CWM was built from ICS source but used on a device that only supported Gingerbread.
It looks like in your case, most of the bricks occurred in an era where Superbrick could not have occurred via the causes we're most familiar with, but I'm wondering if an "alternative" flash/wipe method could have resulted in things getting cratered. (For example, prototype Galaxy Nexus units were hit by fastboot erase cycles - shipped GNexes had safe eMMC firmware.)
Chances are your issue is something unrelated to Superbrick... But it would be interesting if it were.