After we had posted pictures of the Diamond2 and the Touch Pro2, readers have been asking whether or not the change in AT&T’s hardware buttons from the traditional Windows flag found on the un-branded Diamond2 and Touch Pro2 to the Home button found on the original Diamond and Touch Pro would mean that the AT&T version will be stuck in the realm of 6.1 forever, save for the modding over at XDA-Developers. Well, the short answer is that it depends. The full answer after the break.

When Windows Mobile 6.5 was announced, along with the Touch Pro2 and Diamond2, at Mobile World Congress 2009, Microsoft had initially issued a statement that said that only devices with the Windows flag will qualify for a ROM upgrade to 6.5, meaning devices like the Touch Pro and Diamond with the Home button will not be upgradeable. At the same event, HTC announces the Touch Pro2 and Diamond2, stating that an upgrade is planned for those devices.

However, since Mobile World Congress, Microsoft has relaxed its policy and a few months ago the firm has announced a change to its upgrade stance. Now, users do not have to have the Windows flag to receive an upgrade to 6.5. Rather, the upgrade decision will be made at the carrier and device manufacturer level should the device in question meet minimum specifications requirements to run 6.5 smoothly. Those specs include: 400 MHz and 128 MB of RAM.

With the minimum specs, even the Touch Pro/Fuze and Diamond should be upgradeable. However, in the case of the Fuze, it is up to AT&T and HTC to iron out the kinks and decide whether it would make business sense to offer an upgrade.

With branded devices, the upgrade decision rests more on the carrier. Although HTC may roll out upgrades on its own time table for unlocked, HTC-branded devices, the carrier-branded devices get their support from the carriers, not HTC. This adds to the complexity of support and upgrades, including minor software patches and fixes.

With AT&T’s devices, you should ask AT&T and HTC whether an upgrade is planned because Microsoft had already issued its statement that as long as the approval comes from the carrier and the device has a 400 MHz processor with 128 MB of RAM, you have the nod from Redmond, Washington.