[8525, TyTN, MDA Vario II, JasJam Software Upgradin] sn00x:
Although all the information can be found on the forum and in the HTC Hermes Wiki there are always many posts with questions about upgrading and unlocking. I hope this will make it a bit clearer for you:

Bootloader

The bootloader is the place where you can change the low-level software parameters and some hardware parameters of the Hermes, change and read the ROM and provides information about it.

The bootloader is invoked by pressing down both the POWER button and SIDE OK together and using the stylus at the same time to press the RESET button at the bottom.

The bootloader version is shown for a short amount of time when booting the device. You'll see "SPL-1.0X"

Versions

1.04

There is a bug in bootloader 1.04 wich allows you to flash any ROM without a CID check. You have to be in bootloader mode to use this bug.

It's possible to upgrade the RadioROM. You can even flash a patched RadioROM wich is needed to unlock your device.

1.06

The bug from version 1.04 is fixed. Without downgrading to a Shipped ROM with bootloader 1.04 that matches your CID it's not possible to flash a ROM with a different CID.

The RadioROM can't be upgraded. You have to downgrade to bootloader 1.04 to unlock your device.

1.09

You can't downgrade to bootloader 1.04 by flashing a Shipped ROM. However imei-check.co.uk is able to downgrade the bootloader.

There was a solution posted on this forum, but it was stolen from imei-check and was removed. If you are not willing to pay you have to wait until another solution is developed.

The RadioROM can't be upgraded. You have to downgrade to bootloader 1.04 to unlock your device.

CID

The CID your device has varies from operater to operater. It should garantee that only upgrades from a single operater can be installed (to ensure the device is branded etc.)

You can make your device SuperCID wich is some kind of "root-mode". Then you will be able to flash every ROM without thinking about bootloader versions and CIDs.

To find out wich CID your device has use the command "info 2" in bootloader. Read Hermes_BootLoader to know how to use the bootloader.

Preparations

Before you upgrade your ROM (wich will also upgrade your bootloader) you should make your device SuperCID.

Especially if you either upgrade to bootloader 1.06 and there's no Shipped ROM Upgrade with bootloader 1.04 available that matches your CID or upgrade to bootloader 1.09

Unlock / Make your device SuperCID

Use pof's SIM Unlock v2a. This will flash a patched RadioROM that is needed for the unlocking process. Unlock v2a makes your device SuperCID and removes the SIM-Lock.

You need bootloader version 1.04!

The process of flashing the RadioROM and use the unlocker is explained here

There is one restriction:

At the moment it's not possible to unlock X01HT devices wich where bought after 12/1/2006 and have bootloader version 1.09 and RadioROM version 1.14.0.10! Please be patient.

Radio version can be checked from Start->Settings->System->Device Information:Radio Version.

Downgrade Bootloader

If you have bootloader version 1.06 and there is a Shipped ROM Upgrade with bootloader version 1.04 available that matches your CID you can flash it to downgrade your bootloader.

Otherwise - you are on bootloader 1.09 or there is no Shipped ROM Upgrade available - you have to use imei-check.co.uk or wait until another (free) solution is developed.

For the method imei-check uses to downgrade the bootloader a working operating system is required.

Upgrade the ROM

If you flash a ROM the first time you should read Upgrade For Beginners and the Upgrade FAQ if you have further questions.

Available Upgrades are listed here

Upgrade RadioROM

There are also Extracted RadioROMs available. You need bootloader 1.04 to flash these!