[Desire General] aleonty:
Ok, looks like I'm the first:

According to htcdev.com restrictions of official bootloader unlock are:

- not possible to flash custom hboot

- not possible to flash custom radio

considering this I decided that it's not important (those are things with no use to patch) and unlocked the bootloader.

Unlock:

The phone was prepared (2.29.405.14 with appropriate hboot and radio). The unlock RUU worked quickly. The bootloader got pink "***locked***" string after, right in the place where a hello from rev.io was.

I flashed the binary key that I got by email from the htcdev.com site.

Rebooted and got a screen on the phone asking me if I want to unlock the bootloader and offering me to choose yes or no. I chose yes and the phone rebooted.

The bootloader got "***unlocked***" label on top.

The 2.29.405.14 booted ok.

Upgrade:

I tried to flash 2.3.3 RUU from htcdev.com. It finished with errors.

I got images from it and tried to flash them manually image by image:

D:\Android\sdk\platform-tools>fastboot flash boot "d:\android\2.3 htc\rom\boot.img"

sending 'boot' (2516 KB)...

OKAY [ 0.391s]

writing 'boot'...

OKAY [ 0.734s]

finished. total time: 1.125s

D:\Android\sdk\platform-tools>fastboot flash system "d:\android\2.3 htc\rom\system.img"

sending 'system' (244868 KB)...

FAILED (remote: data length is too large)

finished. total time: 0.000s

D:\Android\sdk\platform-tools>fastboot flash recovery "d:\android\2.3 htc\rom\recovery.img"

sending 'recovery' (3098 KB)...

OKAY [ 0.484s]

writing 'recovery'...

OKAY [ 0.891s]

finished. total time: 1.391s

D:\Android\sdk\platform-tools>fastboot flash userdata "d:\android\2.3 htc\rom\userdata.img"

sending 'userdata' (2 KB)...

OKAY [ 0.016s]

writing 'userdata'...

(bootloader) signature checking...

FAILED (remote: signature verify fail)

finished. total time: 0.031s

D:\Android\sdk\platform-tools>fastboot flash rcdata "d:\android\2.3 htc\rom\rcdata.img"

sending 'rcdata' (0 KB)...

OKAY [ 0.016s]

writing 'rcdata'...

(bootloader) signature checking...

FAILED (remote: signature verify fail)

finished. total time: 0.031s

D:\Android\sdk\platform-tools>fastboot flash radio "d:\android\2.3 htc\rom\radio.img"

sending 'radio' (26112 KB)...

OKAY [ 3.922s]

writing 'radio'...

(bootloader) signature checking...

FAILED (remote: signature verify fail)

finished. total time: 7.500s

No need to say that it was not successful but screwed up wifi (apparently boot image flashed ok and it had the kernel that was not compatible with drivers on the old /system filesystem). IMPORTANT! Last official 2.2.2 (2.29.405.5) RUU didn't work either! I took rom.zip from it and flashed boot and recovery manually, it helped.

SO:

Now I have unlocked bootloader and 2.29.405.14 firmware (it's android 2.2.2).

Everything seems to work ok.

I want to flash official 2.3.3 but it has problems with system.img site (apparently will need to repack it).

Another thing: I left an angry opinion on the htc site after irrelevant and not helpful htc support reply concerning the issue with unlocking process. The next day I had a call from htc to know my exact problem and giving my apologies. THAT'S GREAT I think, they really care about customers. (but probably I'll change my opinion after checking the bill for incoming international call on my mobile :)