It's funny, I'm kind of in the same boat, except for 2 "minor" differences:
1) The "Smart Flash" on 4EXT never worked for me (and has consistently corrupted my internal SD card, but been able to fix it each time), so I have S-ON yet
2) I've rooted the phone itself and unlocked the bootloader, but the HBOOT is 1.93.0002, and from what I've seen, the latest firmware patch is .2222 although that really shouldn't matter
This is my 2nd HTC Amaze, and the first time I've gone through the rooting and that, took me at most an hour to complete, including time spent choosing a CMOD (I ended up with 7). This time around...I'm practically pulling my hair out because I cannot perform the S-OFF via Linux (LiveCD of course) nor starting from "square 1". I seem to be in limbo with 4EXT.
I installed Viper Amaze 1.7.2, but continually got stuck on the boot screen. Further investigation revealed that I needed to superCID the phone, which in turn would be to S-OFF first.
Additionally, I've downloaded and flashed the "stock ICS" ROM (since that was my stock ROM to begin with, naturally upgraded ICS), renamed to PH85IMG.zip yadda yadda. It recognizes and loads, but never "updates", more or less does anything after the loading bar on the bootloader.
So, just to try how much I've dug myself in with this, I've downloaded and tried 2 other ROMS, both saying "bad" (no status 7 error like the RUU flash).
I want to try out the Viper Amaze ROM since so much work and effort went into it, and it seriously looks awesome, but because my original tool that I used (HTC Super Tool) didn't require me all of these extra steps (and I didn't remember the program until now), I want to return back to stock so I can start over in a sense and complete those couple of steps that I inadvertently missed. I really feel like I'm missing something stupid.
Out of 7 Android phones that I've completed the custom ROM setup, it has to be this phone...
Anyways, tl;dr here's what I got:
Ruby PVT SHIP S-ON RL
Starting ROM: Wind Mobile ICS 4.0.3 Stock ROM
End ROM: Viper Amaze 1.7.2
Where I'm At: 4EXT, Status 7 error upon stock ROM flash. No other custom ROM works. PH85IMG.zip doesn't seem to do much upon loading via bootloader.