First of all [SD] isn't an uncommon 2 letter combination. There will be several Guilds using this tag, in the past this has never been a problem but in GW2, Guilds are cross server so there is a higher chance of encountering a Guild with the same tag.
It is for this reason that we started talking about changing our tag. We decided to go for [DIUS]. Why this tag? Well, it will be a tag that can only be linked to Semper Dius. If we are seen running around with that tag everyone should instantly know what Guild we are, given that we make a name for ourselves ;)
Another positive from this change is that not only will it make us stand out more in game but also on the internet. If you google SD you'll find a lot of results, if you google Dius we'll be an early hit.
So for those reasons, plus that it looks good and fits us perfectly, we are now officially changing our tag to