Breaking my forum silence for this topic...
These augement gems do something that many have asked for which are better augement gems to drop in quests. However, they fail in a bigger aspect and that is that they have a timer.
As time limited items these are a a bad idea for the following reasons...
A) People rarely want to grind in game for consumables. End game is all about gearing your character out to get better and better. As consumables your guy is not better from these items long term.
B) Time limited items in DDO are rather poor ideas to begin with because they do not count time based upon time equiped in quest, but time logged. This provides disincentives to log on certain toons. This is never a good idea. Already we have XP pots messing with this dynamic on leveling toons (I know I've logged off some of mine with 20% pots going when things were slow to try and save the pot). We certainly don't need a similar mechanic at end game.
C) To really gain benefits from these items it almost has to be assumed that players have unslotted epic items sitting around that they would use over other epic items if they had the right time limited augment. This concept might be logical if epic items were not such an incredible grind to create. It then creates a bizzare incentive not to slot your best items.
All of this adds up to a player being stuck in a sort of limbo. They can't upgrade their cool epic items because they might want to use a temporary augment. They can't log their toons and chat with friends or their temp augments run down. They can't help their buddies bang out some favor on their main, because of augment timers.
This will not result in a fun gaming environment.
My simple suggestion to correct this before it becomes an issue (which it certainly will if this concept is expanded on in the future)...
Improved Augments that drop from quests require copious amounts of epic tokens in addition to the augement itself to slot. For this added cost (having to pull them from a quest instead of just buying them outright) they can have the badly thought out time limit aspect removed from them. There will still be strong reasons to slot 'store bought' augements as they will be much easier to find and if you get an upgrade you can reslot in the upgrade without knowing that you are losing a permenantly good ability for an ability that is better but will fade away leaving you with less then you started with.